diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 8e46595a768..7aab6d6a91d 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2025-06-18 12:17:31 UTC using RuboCop version 1.76.0.
+# on 2025-06-18 13:16:56 UTC using RuboCop version 1.76.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -332,7 +332,7 @@ Rails/FilePath:
     - 'core/lib/spree/testing_support/dummy_app.rb'
     - 'sample/lib/spree/sample.rb'
 
-# Offense count: 59
+# Offense count: 57
 # Configuration parameters: Include.
 # Include: **/app/models/**/*.rb
 Rails/HasManyOrHasOneDependent:
diff --git a/api/spec/requests/spree/api/products_spec.rb b/api/spec/requests/spree/api/products_spec.rb
index 3c6a2f1b89c..072f3a224c1 100644
--- a/api/spec/requests/spree/api/products_spec.rb
+++ b/api/spec/requests/spree/api/products_spec.rb
@@ -200,7 +200,7 @@ module Spree::Api
         required_attributes = json_response["required_attributes"]
         expect(required_attributes).to include("name")
         expect(required_attributes).to include("price")
-        expect(required_attributes).to include("shipping_category_id")
+        expect(required_attributes).to include("shipping_category")
       end
 
       it_behaves_like "modifying product actions are restricted"
@@ -348,7 +348,7 @@ module Spree::Api
           expect(response.status).to eq(422)
           expect(json_response["error"]).to eq("Invalid resource. Please fix errors and try again.")
           errors = json_response["errors"]
-          expect(errors.keys).to include("name", "price", "shipping_category_id")
+          expect(errors.keys).to include("name", "price", "shipping_category")
         end
       end
 
diff --git a/backend/spec/features/admin/orders/customer_details_spec.rb b/backend/spec/features/admin/orders/customer_details_spec.rb
index e3b91f0b2a8..4c77ac4d374 100644
--- a/backend/spec/features/admin/orders/customer_details_spec.rb
+++ b/backend/spec/features/admin/orders/customer_details_spec.rb
@@ -164,7 +164,7 @@
     # Regression test for https://github.com/spree/spree/issues/942
     context "errors when no shipping methods are available" do
       before do
-        Spree::ShippingMethod.delete_all
+        Spree::ShippingMethod.update_all(available_to_all: false, available_to_users: false)
       end
 
       specify do
diff --git a/backend/spec/features/admin/products/products_spec.rb b/backend/spec/features/admin/products/products_spec.rb
index 0e319641f61..f98b6b8c125 100644
--- a/backend/spec/features/admin/products/products_spec.rb
+++ b/backend/spec/features/admin/products/products_spec.rb
@@ -216,7 +216,7 @@ def build_option_type_with_values(name, values)
         fill_in "product_sku", with: "B100"
         fill_in "product_price", with: "100"
         click_button "Create"
-        expect(page).to have_content("Shipping category can't be blank")
+        expect(page).to have_content("Shipping Category must exist")
       end
 
       context "using a locale with a different decimal format " do
diff --git a/core/app/models/spree/product.rb b/core/app/models/spree/product.rb
index 8fd536353dc..657e9f92b68 100644
--- a/core/app/models/spree/product.rb
+++ b/core/app/models/spree/product.rb
@@ -31,7 +31,7 @@ class Product < Spree::Base
     has_many :taxons, through: :classifications, before_remove: :remove_taxon
 
     belongs_to :tax_category, class_name: 'Spree::TaxCategory', optional: true
-    belongs_to :shipping_category, class_name: 'Spree::ShippingCategory', inverse_of: :products, optional: true
+    belongs_to :shipping_category, class_name: 'Spree::ShippingCategory', inverse_of: :products
     belongs_to :primary_taxon, class_name: 'Spree::Taxon', optional: true
 
     has_one :master,
@@ -122,7 +122,6 @@ def find_or_build_master
     validates :meta_title, length: { maximum: 255 }
     validates :name, presence: true
     validates :price, presence: true, if: proc { Spree::Config[:require_master_price] }
-    validates :shipping_category_id, presence: true
     validates :slug, presence: true, uniqueness: { allow_blank: true, case_sensitive: true }
 
     attr_accessor :option_values_hash
diff --git a/core/app/models/spree/shipping_category.rb b/core/app/models/spree/shipping_category.rb
index 8d5da64979f..532f3ebec82 100644
--- a/core/app/models/spree/shipping_category.rb
+++ b/core/app/models/spree/shipping_category.rb
@@ -5,8 +5,8 @@ class ShippingCategory < Spree::Base
     self.allowed_ransackable_attributes = %w[name]
 
     validates :name, presence: true
-    has_many :products, inverse_of: :shipping_category
-    has_many :shipping_method_categories, inverse_of: :shipping_category
+    has_many :products, inverse_of: :shipping_category, dependent: :restrict_with_error
+    has_many :shipping_method_categories, inverse_of: :shipping_category, dependent: :destroy
     has_many :shipping_methods, through: :shipping_method_categories
   end
 end
diff --git a/core/app/models/spree/shipping_method_category.rb b/core/app/models/spree/shipping_method_category.rb
index 0a4072243a7..0d67a34506f 100644
--- a/core/app/models/spree/shipping_method_category.rb
+++ b/core/app/models/spree/shipping_method_category.rb
@@ -2,7 +2,7 @@
 
 module Spree
   class ShippingMethodCategory < Spree::Base
-    belongs_to :shipping_method, class_name: 'Spree::ShippingMethod', optional: true
-    belongs_to :shipping_category, class_name: 'Spree::ShippingCategory', inverse_of: :shipping_method_categories, optional: true
+    belongs_to :shipping_method, class_name: 'Spree::ShippingMethod'
+    belongs_to :shipping_category, class_name: 'Spree::ShippingCategory', inverse_of: :shipping_method_categories
   end
 end
diff --git a/core/db/migrate/20250605105424_add_shipping_category_foreign_keys.rb b/core/db/migrate/20250605105424_add_shipping_category_foreign_keys.rb
new file mode 100644
index 00000000000..baf77136f2f
--- /dev/null
+++ b/core/db/migrate/20250605105424_add_shipping_category_foreign_keys.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class AddShippingCategoryForeignKeys < ActiveRecord::Migration[7.0]
+  def change
+    add_foreign_key :spree_products, :spree_shipping_categories, column: :shipping_category_id, null: false
+    add_foreign_key :spree_shipping_method_categories, :spree_shipping_methods, column: :shipping_method_id, null: false
+    add_foreign_key :spree_shipping_method_categories, :spree_shipping_categories, column: :shipping_category_id, null: false
+  end
+end