diff --git a/packages/repository-tests/src/crud/create-retrieve.suite.ts b/packages/repository-tests/src/crud/create-retrieve.suite.ts
index 7ec364f8b6d6..6334fd0af4d4 100644
--- a/packages/repository-tests/src/crud/create-retrieve.suite.ts
+++ b/packages/repository-tests/src/crud/create-retrieve.suite.ts
@@ -87,7 +87,7 @@ export function createRetrieveSuite(
     it('retrieves an instance of a model from its foreign key value', async () => {
       const pens = await repo.create({name: 'Pens', categoryId: 1});
       const pencils = await repo.create({name: 'Pencils', categoryId: 2});
-      const products = await findByForeignKeys(repo, 'categoryId', [1]);
+      const products = await findByForeignKeys(repo, 'categoryId', 1);
       expect(products).deepEqual([pens]);
       expect(products).to.not.containDeep(pencils);
     });
diff --git a/packages/repository/src/__tests__/unit/repositories/relation.helpers.unit.ts b/packages/repository/src/__tests__/unit/repositories/relation.helpers.unit.ts
index 216b3f7ff397..fa8cd92ee4ab 100644
--- a/packages/repository/src/__tests__/unit/repositories/relation.helpers.unit.ts
+++ b/packages/repository/src/__tests__/unit/repositories/relation.helpers.unit.ts
@@ -21,25 +21,39 @@ describe('findByForeignKeys', () => {
 
   it('returns an empty array when no instances have the foreign key value', async () => {
     await productRepo.create({id: 1, name: 'product', categoryId: 1});
-    const products = await findByForeignKeys(productRepo, 'categoryId', [2]);
+    const products = await findByForeignKeys(productRepo, 'categoryId', 2);
+    expect(products).to.be.empty();
+  });
+
+  it('returns an empty array when no instances have the foreign key values', async () => {
+    await productRepo.create({id: 1, name: 'product', categoryId: 1});
+    const products = await findByForeignKeys(productRepo, 'categoryId', [2, 3]);
     expect(products).to.be.empty();
   });
 
   it('returns all instances that have the foreign key value', async () => {
     const pens = await productRepo.create({name: 'pens', categoryId: 1});
     const pencils = await productRepo.create({name: 'pencils', categoryId: 1});
-    const products = await findByForeignKeys(productRepo, 'categoryId', [1]);
+    const products = await findByForeignKeys(productRepo, 'categoryId', 1);
     expect(products).to.deepEqual([pens, pencils]);
   });
 
   it('does not include instances with different foreign key values', async () => {
     const pens = await productRepo.create({name: 'pens', categoryId: 1});
     const pencils = await productRepo.create({name: 'pencils', categoryId: 2});
-    const products = await findByForeignKeys(productRepo, 'categoryId', [1]);
+    const products = await findByForeignKeys(productRepo, 'categoryId', 1);
     expect(products).to.deepEqual([pens]);
     expect(products).to.not.containDeep(pencils);
   });
 
+  it('includes instances when there is one value in the array of foreign key values', async () => {
+    const pens = await productRepo.create({name: 'pens', categoryId: 1});
+    const pencils = await productRepo.create({name: 'pencils', categoryId: 2});
+    const products = await findByForeignKeys(productRepo, 'categoryId', [2]);
+    expect(products).to.deepEqual([pencils]);
+    expect(products).to.not.containDeep(pens);
+  });
+
   it('returns all instances that have any of multiple foreign key values', async () => {
     const pens = await productRepo.create({name: 'pens', categoryId: 1});
     const pencils = await productRepo.create({name: 'pencils', categoryId: 2});
@@ -61,6 +75,20 @@ describe('findByForeignKeys', () => {
     expect(errorMessage).to.eql('scope is not supported');
   });
 
+  it('does not throw an error if scope is passed in and is undefined or empty', async () => {
+    let products = await findByForeignKeys(
+      productRepo,
+      'categoryId',
+      [1],
+      undefined,
+      {},
+    );
+    expect(products).to.be.empty();
+
+    products = await findByForeignKeys(productRepo, 'categoryId', 1, {}, {});
+    expect(products).to.be.empty();
+  });
+
   /******************* HELPERS *******************/
 
   @model()
diff --git a/packages/repository/src/relations/relation.helpers.ts b/packages/repository/src/relations/relation.helpers.ts
index 921c27570d19..e15aaf90a3ba 100644
--- a/packages/repository/src/relations/relation.helpers.ts
+++ b/packages/repository/src/relations/relation.helpers.ts
@@ -11,19 +11,18 @@ import {Entity, EntityCrudRepository, Filter, Options, Where} from '..';
  *
  * @param targetRepository - The target repository where the model instances are found
  * @param fkName - Name of the foreign key
- * @param fkValues - Array of the values of the foreign keys to be included
+ * @param fkValues - One value or array of values of the foreign keys to be included
  * @param scope - Additional scope constraints (not currently supported)
  * @param options - Options for the operations
  */
 export async function findByForeignKeys<
   Target extends Entity,
-  TargetID,
   TargetRelations extends object,
-  ForeignKey
+  ForeignKey extends StringKeyOf<Target>
 >(
-  targetRepository: EntityCrudRepository<Target, TargetID, TargetRelations>,
-  fkName: StringKeyOf<Target>,
-  fkValues: ForeignKey[],
+  targetRepository: EntityCrudRepository<Target, unknown, TargetRelations>,
+  fkName: ForeignKey,
+  fkValues: Target[ForeignKey][] | Target[ForeignKey],
   scope?: Filter<Target>,
   options?: Options,
 ): Promise<(Target & TargetRelations)[]> {
@@ -33,9 +32,13 @@ export async function findByForeignKeys<
     throw new Error('scope is not supported');
   }
 
-  const where = ({
-    [fkName]: fkValues.length === 1 ? fkValues[0] : {inq: fkValues},
-  } as unknown) as Where<Target>;
+  const value = Array.isArray(fkValues)
+    ? fkValues.length === 1
+      ? fkValues[0]
+      : {inq: fkValues}
+    : fkValues;
+
+  const where = ({[fkName]: value} as unknown) as Where<Target>;
   const targetFilter = {where};
 
   return targetRepository.find(targetFilter, options);