diff --git a/src/datasources/product-api.ts b/src/datasources/product-api.ts
index eb25911..0d848ae 100644
--- a/src/datasources/product-api.ts
+++ b/src/datasources/product-api.ts
@@ -536,4 +536,32 @@ export class ProductAPI extends BaseSQLDataSource {
     promises.push(query);
     return Promise.all(promises);
   }
+
+  async addCategoriesToProduct(
+    productId,
+    categoryIds,
+  ): Promise<Promise<void>[]> {
+    const promises = categoryIds.map((categoryId) =>
+      this.knex('product_category').insert({
+        product_id: productId,
+        category_id: categoryId,
+      }),
+    );
+    return Promise.all(promises);
+  }
+
+  async removeCategoriesFromProduct(
+    productId,
+    categoryIds,
+  ): Promise<Promise<void>[]> {
+    const promises = categoryIds.map((categoryId) =>
+      this.knex('product_category')
+        .where({
+          product_id: productId,
+          category_id: categoryId,
+        })
+        .del(),
+    );
+    return Promise.all(promises);
+  }
 }
diff --git a/src/resolvers/products-resolver.ts b/src/resolvers/products-resolver.ts
index cd65f2a..89d9b8f 100644
--- a/src/resolvers/products-resolver.ts
+++ b/src/resolvers/products-resolver.ts
@@ -180,4 +180,24 @@ export const productMutationTypeDefs = {
     );
     return (<ProductAPI>dataSources.productApi).getProduct(productId);
   },
+
+  async addCategoriesToProduct(_, { productId, categoryIds }, { dataSources }) {
+    await (<ProductAPI>dataSources.productApi).addCategoriesToProduct(
+      productId,
+      categoryIds,
+    );
+    return (<ProductAPI>dataSources.productApi).getProduct(productId);
+  },
+
+  async removeCategoriesFromProduct(
+    _,
+    { productId, categoryIds },
+    { dataSources },
+  ) {
+    await (<ProductAPI>dataSources.productApi).removeCategoriesFromProduct(
+      productId,
+      categoryIds,
+    );
+    return (<ProductAPI>dataSources.productApi).getProduct(productId);
+  },
 };
diff --git a/src/schema.graphql b/src/schema.graphql
index 1c58151..8161702 100644
--- a/src/schema.graphql
+++ b/src/schema.graphql
@@ -459,4 +459,7 @@ type Mutation {
   removeRelatedProducts(productId: Int!, relatedProductIds: [Int]!): Product
 
   addKeyword(name: String!, type: KeywordType): Keyword
+
+  addCategoriesToProduct(productId: Int!, categoryIds: [Int]!): Product
+  removeCategoriesFromProduct(productId: Int!, categoryIds: [Int]!): Product
 }