diff --git a/plugins/woocommerce/changelog/41253-as-update-to-php-81 b/plugins/woocommerce/changelog/41253-as-update-to-php-81
new file mode 100644
index 00000000000..e8be4d9b37e
--- /dev/null
+++ b/plugins/woocommerce/changelog/41253-as-update-to-php-81
@@ -0,0 +1,4 @@
+Significance: patch
+Type: dev
+
+Apply type checks and enhancements for PHP 8.1
diff --git a/plugins/woocommerce/includes/admin/class-wc-admin-importers.php b/plugins/woocommerce/includes/admin/class-wc-admin-importers.php
index 2d2886afe99..37c59e4dc5b 100644
--- a/plugins/woocommerce/includes/admin/class-wc-admin-importers.php
+++ b/plugins/woocommerce/includes/admin/class-wc-admin-importers.php
@@ -293,11 +293,11 @@ class WC_Admin_Importers {
 					'position'            => 'done',
 					'percentage'          => 100,
 					'url'                 => add_query_arg( array( '_wpnonce' => wp_create_nonce( 'woocommerce-csv-importer' ) ), admin_url( 'edit.php?post_type=product&page=product_importer&step=done' ) ),
-					'imported'            => count( $results['imported'] ),
-					'imported_variations' => count( $results['imported_variations'] ),
-					'failed'              => count( $results['failed'] ),
-					'updated'             => count( $results['updated'] ),
-					'skipped'             => count( $results['skipped'] ),
+					'imported'            => is_countable( $results['imported'] ) ? count( $results['imported'] ) : 0,
+					'imported_variations' => is_countable( $results['imported_variations'] ) ? count( $results['imported_variations'] ) : 0,
+					'failed'              => is_countable( $results['failed'] ) ? count( $results['failed'] ) : 0,
+					'updated'             => is_countable( $results['updated'] ) ? count( $results['updated'] ) : 0,
+					'skipped'             => is_countable( $results['skipped'] ) ? count( $results['skipped'] ) : 0,
 				)
 			);
 		} else {
@@ -305,11 +305,11 @@ class WC_Admin_Importers {
 				array(
 					'position'            => $importer->get_file_position(),
 					'percentage'          => $percent_complete,
-					'imported'            => count( $results['imported'] ),
-					'imported_variations' => count( $results['imported_variations'] ),
-					'failed'              => count( $results['failed'] ),
-					'updated'             => count( $results['updated'] ),
-					'skipped'             => count( $results['skipped'] ),
+					'imported'            => is_countable( $results['imported'] ) ? count( $results['imported'] ) : 0,
+					'imported_variations' => is_countable( $results['imported_variations'] ) ? count( $results['imported_variations'] ) : 0,
+					'failed'              => is_countable( $results['failed'] ) ? count( $results['failed'] ) : 0,
+					'updated'             => is_countable( $results['updated'] ) ? count( $results['updated'] ) : 0,
+					'skipped'             => is_countable( $results['skipped'] ) ? count( $results['skipped'] ) : 0,
 				)
 			);
 		}
diff --git a/plugins/woocommerce/includes/admin/class-wc-admin-webhooks.php b/plugins/woocommerce/includes/admin/class-wc-admin-webhooks.php
index d5c4862963d..8feac7bc5a6 100644
--- a/plugins/woocommerce/includes/admin/class-wc-admin-webhooks.php
+++ b/plugins/woocommerce/includes/admin/class-wc-admin-webhooks.php
@@ -192,7 +192,7 @@ class WC_Admin_Webhooks {
 			$webhook_id = absint( $_GET['delete'] );
 
 			if ( $webhook_id ) {
-				$this->bulk_delete( array( $webhook_id ) );
+				self::bulk_delete( array( $webhook_id ) );
 			}
 		}
 	}
diff --git a/plugins/woocommerce/includes/admin/helper/class-wc-helper.php b/plugins/woocommerce/includes/admin/helper/class-wc-helper.php
index f93ab209cd7..fd264411104 100644
--- a/plugins/woocommerce/includes/admin/helper/class-wc-helper.php
+++ b/plugins/woocommerce/includes/admin/helper/class-wc-helper.php
@@ -408,7 +408,7 @@ class WC_Helper {
 		}
 
 		$filters = array_fill_keys( array_keys( self::get_filters() ), 0 );
-		if ( empty( $subscriptions ) ) {
+		if ( ! is_array( $subscriptions ) || empty( $subscriptions ) ) {
 			return array();
 		}
 
@@ -1461,7 +1461,7 @@ class WC_Helper {
 				if ( is_readable( $txt ) ) {
 					$txt = file_get_contents( $txt );
 					$txt = preg_split( '#\s#', $txt );
-					if ( count( $txt ) >= 2 ) {
+					if ( is_array( $txt ) && count( $txt ) >= 2 ) {
 						$header = sprintf( '%d:%s', $txt[0], $txt[1] );
 					}
 				}
diff --git a/plugins/woocommerce/includes/admin/importers/class-wc-tax-rate-importer.php b/plugins/woocommerce/includes/admin/importers/class-wc-tax-rate-importer.php
index e07375ffd97..a32b9e9d5d7 100644
--- a/plugins/woocommerce/includes/admin/importers/class-wc-tax-rate-importer.php
+++ b/plugins/woocommerce/includes/admin/importers/class-wc-tax-rate-importer.php
@@ -146,8 +146,8 @@ class WC_Tax_Rate_Importer extends WP_Importer {
 		if ( false !== $handle ) {
 
 			$header = fgetcsv( $handle, 0, $this->delimiter );
-
-			if ( 10 === count( $header ) ) {
+			$count  = is_countable( $header ) ? count( $header ) : 0;
+			if ( 10 === $count ) {
 
 				$row = fgetcsv( $handle, 0, $this->delimiter );
 
diff --git a/plugins/woocommerce/includes/admin/importers/views/html-csv-import-done.php b/plugins/woocommerce/includes/admin/importers/views/html-csv-import-done.php
index 70ef0ddd651..d74a37eebd7 100644
--- a/plugins/woocommerce/includes/admin/importers/views/html-csv-import-done.php
+++ b/plugins/woocommerce/includes/admin/importers/views/html-csv-import-done.php
@@ -80,7 +80,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 			</thead>
 			<tbody>
 				<?php
-				if ( count( $errors ) ) {
+				if ( is_array( $errors ) && count( $errors ) ) {
 					foreach ( $errors as $error ) {
 						if ( ! is_wp_error( $error ) ) {
 							continue;
diff --git a/plugins/woocommerce/includes/admin/list-tables/class-wc-admin-list-table-coupons.php b/plugins/woocommerce/includes/admin/list-tables/class-wc-admin-list-table-coupons.php
index f2b16a78c7b..3c438f4c503 100644
--- a/plugins/woocommerce/includes/admin/list-tables/class-wc-admin-list-table-coupons.php
+++ b/plugins/woocommerce/includes/admin/list-tables/class-wc-admin-list-table-coupons.php
@@ -136,8 +136,7 @@ class WC_Admin_List_Table_Coupons extends WC_Admin_List_Table {
 	 */
 	protected function render_products_column() {
 		$product_ids = $this->object->get_product_ids();
-
-		if ( count( $product_ids ) > 0 ) {
+		if ( is_array( $product_ids ) && count( $product_ids ) > 0 ) {
 			echo esc_html( implode( ', ', $product_ids ) );
 		} else {
 			echo '&ndash;';
diff --git a/plugins/woocommerce/includes/admin/meta-boxes/views/html-product-data-variations.php b/plugins/woocommerce/includes/admin/meta-boxes/views/html-product-data-variations.php
index dca2695ca46..3292ec3d1d6 100644
--- a/plugins/woocommerce/includes/admin/meta-boxes/views/html-product-data-variations.php
+++ b/plugins/woocommerce/includes/admin/meta-boxes/views/html-product-data-variations.php
@@ -15,8 +15,7 @@ $arrow_img_url          = WC_ADMIN_IMAGES_FOLDER_URL . '/product_data/no-variati
 ?>
 <div id="variable_product_options" class="panel wc-metaboxes-wrapper hidden">
 	<div id="variable_product_options_inner">
-
-		<?php if ( ! count( $variation_attributes ) ) : ?>
+		<?php if ( ! isset( $variation_attributes ) || ! is_array( $variation_attributes ) || count( $variation_attributes ) === 0 ) : ?>
 
 		<div class="add-attributes-container">
 			<div class="add-attributes-message">
diff --git a/plugins/woocommerce/includes/admin/reports/class-wc-report-sales-by-category.php b/plugins/woocommerce/includes/admin/reports/class-wc-report-sales-by-category.php
index dda8c193885..51ed4f8c2da 100644
--- a/plugins/woocommerce/includes/admin/reports/class-wc-report-sales-by-category.php
+++ b/plugins/woocommerce/includes/admin/reports/class-wc-report-sales-by-category.php
@@ -343,7 +343,7 @@ class WC_Report_Sales_By_Category extends WC_Admin_Report {
 								$index = 0;
 								foreach ( $chart_data as $data ) {
 									$color  = isset( $this->chart_colours[ $index ] ) ? $this->chart_colours[ $index ] : $this->chart_colours[0];
-									$width  = $this->barwidth / sizeof( $chart_data );
+									$width  = $this->barwidth / count( $chart_data );
 									$offset = ( $width * $index );
 									$series = $data['data'];
 
diff --git a/plugins/woocommerce/includes/admin/settings/class-wc-settings-tax.php b/plugins/woocommerce/includes/admin/settings/class-wc-settings-tax.php
index ad195eb9348..5ab6a38c3a5 100644
--- a/plugins/woocommerce/includes/admin/settings/class-wc-settings-tax.php
+++ b/plugins/woocommerce/includes/admin/settings/class-wc-settings-tax.php
@@ -178,7 +178,7 @@ class WC_Settings_Tax extends WC_Settings_Page {
 	public function output_tax_rates() {
 		global $current_section;
 
-		$current_class = $this->get_current_tax_class();
+		$current_class = self::get_current_tax_class();
 
 		$countries = array();
 		foreach ( WC()->countries->get_allowed_countries() as $value => $label ) {
@@ -320,7 +320,7 @@ class WC_Settings_Tax extends WC_Settings_Page {
 		// phpcs:disable WordPress.Security.NonceVerification.Missing -- this is called via "do_action('woocommerce_settings_save_'...") in base class, where nonce is verified first.
 		global $wpdb;
 
-		$current_class = sanitize_title( $this->get_current_tax_class() );
+		$current_class = sanitize_title( self::get_current_tax_class() );
 		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotValidated, WordPress.Security.NonceVerification.Missing
 		$posted_countries = wc_clean( wp_unslash( $_POST['tax_rate_country'] ) );
 
diff --git a/plugins/woocommerce/includes/admin/views/html-admin-page-status-report.php b/plugins/woocommerce/includes/admin/views/html-admin-page-status-report.php
index f97619e7687..ec6ae5459f5 100644
--- a/plugins/woocommerce/includes/admin/views/html-admin-page-status-report.php
+++ b/plugins/woocommerce/includes/admin/views/html-admin-page-status-report.php
@@ -25,6 +25,10 @@ $logging            = $report['logging'];
 $wp_pages           = $report['pages'];
 $plugin_updates     = new WC_Plugin_Updates();
 $untested_plugins   = $plugin_updates->get_untested_plugins( WC()->version, Constants::get_constant( 'WC_SSR_PLUGIN_UPDATE_RELEASE_VERSION_TYPE' ) );
+
+$active_plugins_count   = is_countable( $active_plugins ) ? count( $active_plugins ) : 0;
+$inactive_plugins_count = is_countable( $inactive_plugins ) ? count( $inactive_plugins ) : 0;
+
 ?>
 <div class="updated woocommerce-message inline">
 	<p>
@@ -575,7 +579,7 @@ $untested_plugins   = $plugin_updates->get_untested_plugins( WC()->version, Cons
 <table class="wc_status_table widefat" cellspacing="0">
 	<thead>
 		<tr>
-			<th colspan="3" data-export-label="Active Plugins (<?php echo count( $active_plugins ); ?>)"><h2><?php esc_html_e( 'Active plugins', 'woocommerce' ); ?> (<?php echo count( $active_plugins ); ?>)</h2></th>
+			<th colspan="3" data-export-label="Active Plugins (<?php echo esc_attr( $active_plugins_count ); ?>)"><h2><?php esc_html_e( 'Active plugins', 'woocommerce' ); ?> (<?php echo esc_attr( $active_plugins_count ); ?>)</h2></th>
 		</tr>
 	</thead>
 	<tbody>
@@ -585,7 +589,7 @@ $untested_plugins   = $plugin_updates->get_untested_plugins( WC()->version, Cons
 <table class="wc_status_table widefat" cellspacing="0">
 	<thead>
 		<tr>
-			<th colspan="3" data-export-label="Inactive Plugins (<?php echo count( $inactive_plugins ); ?>)"><h2><?php esc_html_e( 'Inactive plugins', 'woocommerce' ); ?> (<?php echo count( $inactive_plugins ); ?>)</h2></th>
+			<th colspan="3" data-export-label="Inactive Plugins (<?php echo esc_attr( $inactive_plugins_count ); ?>)"><h2><?php esc_html_e( 'Inactive plugins', 'woocommerce' ); ?> (<?php echo esc_attr( $inactive_plugins_count ); ?>)</h2></th>
 		</tr>
 	</thead>
 	<tbody>
@@ -593,12 +597,13 @@ $untested_plugins   = $plugin_updates->get_untested_plugins( WC()->version, Cons
 	</tbody>
 </table>
 <?php
-if ( 0 < count( $dropins_mu_plugins['dropins'] ) ) :
+$dropins_count = is_countable( $dropins_mu_plugins['dropins'] ) ? count( $dropins_mu_plugins['dropins'] ) : 0;
+if ( 0 < $dropins_count ) :
 	?>
 	<table class="wc_status_table widefat" cellspacing="0">
 		<thead>
 			<tr>
-				<th colspan="3" data-export-label="Dropin Plugins (<?php echo count( $dropins_mu_plugins['dropins'] ); ?>)"><h2><?php esc_html_e( 'Dropin Plugins', 'woocommerce' ); ?> (<?php echo count( $dropins_mu_plugins['dropins'] ); ?>)</h2></th>
+				<th colspan="3" data-export-label="Dropin Plugins (<?php $dropins_count; ?>)"><h2><?php esc_html_e( 'Dropin Plugins', 'woocommerce' ); ?> (<?php $dropins_count; ?>)</h2></th>
 			</tr>
 		</thead>
 		<tbody>
@@ -617,12 +622,14 @@ if ( 0 < count( $dropins_mu_plugins['dropins'] ) ) :
 	</table>
 	<?php
 endif;
-if ( 0 < count( $dropins_mu_plugins['mu_plugins'] ) ) :
+
+$mu_plugins_count = is_countable( $dropins_mu_plugins['mu_plugins'] ) ? count( $dropins_mu_plugins['mu_plugins'] ) : 0;
+if ( 0 < $mu_plugins_count ) :
 	?>
 	<table class="wc_status_table widefat" cellspacing="0">
 		<thead>
 			<tr>
-				<th colspan="3" data-export-label="Must Use Plugins (<?php echo count( $dropins_mu_plugins['mu_plugins'] ); ?>)"><h2><?php esc_html_e( 'Must Use Plugins', 'woocommerce' ); ?> (<?php echo count( $dropins_mu_plugins['mu_plugins'] ); ?>)</h2></th>
+				<th colspan="3" data-export-label="Must Use Plugins (<?php echo esc_attr( $mu_plugins_count ); ?>)"><h2><?php esc_html_e( 'Must Use Plugins', 'woocommerce' ); ?> (<?php echo esc_attr( $mu_plugins_count ); ?>)</h2></th>
 			</tr>
 		</thead>
 		<tbody>
@@ -959,7 +966,7 @@ if ( 0 < count( $dropins_mu_plugins['mu_plugins'] ) ) :
 				<td class="help">&nbsp;</td>
 				<td>
 					<?php
-					$total_overrides = count( $theme['overrides'] );
+					$total_overrides = is_countable( $theme['overrides'] ) ? count( $theme['overrides'] ) : 0;
 					for ( $i = 0; $i < $total_overrides; $i++ ) {
 						$override = $theme['overrides'][ $i ];
 						if ( $override['core_version'] && ( empty( $override['version'] ) || version_compare( $override['version'], $override['core_version'], '<' ) ) ) {
@@ -974,7 +981,8 @@ if ( 0 < count( $dropins_mu_plugins['mu_plugins'] ) ) :
 						} else {
 							echo esc_html( $override['file'] );
 						}
-						if ( ( count( $theme['overrides'] ) - 1 ) !== $i ) {
+
+						if ( ( $total_overrides - 1 ) !== $i ) {
 							echo ', ';
 						}
 						echo '<br />';
diff --git a/plugins/woocommerce/includes/class-wc-ajax.php b/plugins/woocommerce/includes/class-wc-ajax.php
index 8d4ba1998a5..13d6cb53c47 100644
--- a/plugins/woocommerce/includes/class-wc-ajax.php
+++ b/plugins/woocommerce/includes/class-wc-ajax.php
@@ -2064,7 +2064,8 @@ class WC_AJAX {
 
 		$children = get_terms( $taxonomy, "child_of=$id&menu_order=ASC&hide_empty=0" );
 
-		if ( $term && count( $children ) ) {
+		$children_count = is_countable( $children ) ? count( $children ) : 0;
+		if ( $term && $children_count ) {
 			echo 'children';
 			wp_die();
 		}
diff --git a/plugins/woocommerce/includes/class-wc-deprecated-action-hooks.php b/plugins/woocommerce/includes/class-wc-deprecated-action-hooks.php
index 39bc932608f..1cc7f85306b 100644
--- a/plugins/woocommerce/includes/class-wc-deprecated-action-hooks.php
+++ b/plugins/woocommerce/includes/class-wc-deprecated-action-hooks.php
@@ -175,14 +175,6 @@ class WC_Deprecated_Action_Hooks extends WC_Deprecated_Hooks {
 					do_action( $old_hook, $order_id, $item_id, $item, $item->get_product() );
 				}
 				break;
-			case 'woocommerce_order_update_coupon':
-			case 'woocommerce_order_update_shipping':
-			case 'woocommerce_order_update_fee':
-			case 'woocommerce_order_update_tax':
-				if ( ! is_a( $item, 'WC_Order_Item_Product' ) ) {
-					do_action( $old_hook, $order_id, $item_id, $item );
-				}
-				break;
 			default:
 				do_action_ref_array( $old_hook, $new_callback_args );
 				break;
diff --git a/plugins/woocommerce/includes/class-wc-geo-ip.php b/plugins/woocommerce/includes/class-wc-geo-ip.php
index d856be2848a..392025a83f7 100644
--- a/plugins/woocommerce/includes/class-wc-geo-ip.php
+++ b/plugins/woocommerce/includes/class-wc-geo-ip.php
@@ -1194,7 +1194,7 @@ class WC_Geo_IP {
 					$this->memory_buffer = fread( $this->filehandle, $s_array['size'] );
 				}
 			} else {
-				$this->log( 'GeoIP API: Can not open ' . $filename, 'error' );
+				self::log( 'GeoIP API: Can not open ' . $filename, 'error' );
 			}
 		}
 
@@ -1553,7 +1553,7 @@ class WC_Geo_IP {
 			}
 		}
 
-		$this->log( 'GeoIP API: Error traversing database - perhaps it is corrupt?', 'error' );
+		self::log( 'GeoIP API: Error traversing database - perhaps it is corrupt?', 'error' );
 
 		return false;
 	}
@@ -1608,7 +1608,7 @@ class WC_Geo_IP {
 			}
 		}
 
-		$this->log( 'GeoIP API: Error traversing database - perhaps it is corrupt?', 'error' );
+		self::log( 'GeoIP API: Error traversing database - perhaps it is corrupt?', 'error' );
 
 		return false;
 	}
@@ -1637,7 +1637,7 @@ class WC_Geo_IP {
 	 */
 	public function geoip_country_id_by_addr_v6( $addr ) {
 		if ( ! defined( 'AF_INET6' ) ) {
-			$this->log( 'GEOIP (geoip_country_id_by_addr_v6): PHP was compiled with --disable-ipv6 option' );
+			self::log( 'GEOIP (geoip_country_id_by_addr_v6): PHP was compiled with --disable-ipv6 option' );
 			return false;
 		}
 		$ipnum = inet_pton( $addr );