diff --git a/.changeset/slimy-days-leave.md b/.changeset/slimy-days-leave.md
index 250bf32962..df772d80d4 100644
--- a/.changeset/slimy-days-leave.md
+++ b/.changeset/slimy-days-leave.md
@@ -2,4 +2,4 @@
 '@backstage/plugin-catalog-backend': patch
 ---
 
-Allow nested EntityFilters
+Allow singleton and flexibly nested EntityFilters
diff --git a/plugins/catalog-backend/api-report.md b/plugins/catalog-backend/api-report.md
index e83fa68cad..143e31bc21 100644
--- a/plugins/catalog-backend/api-report.md
+++ b/plugins/catalog-backend/api-report.md
@@ -870,11 +870,14 @@ export type EntityAncestryResponse = {
 // Warning: (ae-missing-release-tag) "EntityFilter" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
 // @public
-export type EntityFilter = {
-  anyOf: {
-    allOf: (EntitiesSearchFilter | EntityFilter)[];
-  }[];
-};
+export type EntityFilter =
+  | {
+      allOf: EntityFilter[];
+    }
+  | {
+      anyOf: EntityFilter[];
+    }
+  | EntitiesSearchFilter;
 
 // Warning: (ae-missing-release-tag) "EntityPagination" is exported by the package, but it is missing a release tag (@alpha, @beta, @public, or @internal)
 //
diff --git a/plugins/catalog-backend/src/catalog/types.ts b/plugins/catalog-backend/src/catalog/types.ts
index b0b06c563c..df693bfd42 100644
--- a/plugins/catalog-backend/src/catalog/types.ts
+++ b/plugins/catalog-backend/src/catalog/types.ts
@@ -22,9 +22,10 @@ import { Entity, EntityRelationSpec } from '@backstage/catalog-model';
  * Any (at least one) of the outer sets must match, within which all of the
  * individual filters must match.
  */
-export type EntityFilter = {
-  anyOf: { allOf: (EntitiesSearchFilter | EntityFilter)[] }[];
-};
+export type EntityFilter =
+  | { allOf: EntityFilter[] }
+  | { anyOf: EntityFilter[] }
+  | EntitiesSearchFilter;
 
 /**
  * A pagination rule for entities.
diff --git a/plugins/catalog-backend/src/legacy/database/CommonDatabase.ts b/plugins/catalog-backend/src/legacy/database/CommonDatabase.ts
index 81b0612989..6a150f7583 100644
--- a/plugins/catalog-backend/src/legacy/database/CommonDatabase.ts
+++ b/plugins/catalog-backend/src/legacy/database/CommonDatabase.ts
@@ -46,11 +46,11 @@ import {
   DbPageInfo,
   Transaction,
 } from './types';
-import {
-  EntityPagination,
-  EntityFilter,
-  EntitiesSearchFilter,
-} from '../../catalog/types';
+import { EntityPagination, EntitiesSearchFilter } from '../../catalog/types';
+
+type LegacyEntityFilter = {
+  anyOf: { allOf: EntitiesSearchFilter[] }[];
+};
 
 // The number of items that are sent per batch to the database layer, when
 // doing .batchInsert calls to knex. This needs to be low enough to not cause
@@ -221,10 +221,23 @@ export class CommonDatabase implements Database {
 
     let entitiesQuery = tx<DbEntitiesRow>('entities');
 
-    for (const singleFilter of request?.filter?.anyOf ?? []) {
+    if (
+      request?.filter &&
+      (request.filter.hasOwnProperty('key') ||
+        request.filter.hasOwnProperty('allOf'))
+    ) {
+      throw new Error(
+        'Filters for the legacy CommonDatabase must obey the { anyOf: [{ allOf: [] }] } format.',
+      );
+    }
+    for (const singleFilter of (request?.filter as LegacyEntityFilter)?.anyOf ??
+      []) {
       entitiesQuery = entitiesQuery.orWhere(function singleFilterFn() {
         for (const filter of singleFilter.allOf) {
-          if (isEntityFilter(filter)) {
+          if (
+            filter.hasOwnProperty('anyOf') ||
+            filter.hasOwnProperty('allOf')
+          ) {
             throw new Error(
               'Nested filters are not supported in the legacy CommonDatabase',
             );
@@ -612,9 +625,3 @@ function deduplicateRelations(
     r => `${r.source_full_name}:${r.target_full_name}:${r.type}`,
   );
 }
-
-function isEntityFilter(
-  filter: EntitiesSearchFilter | EntityFilter,
-): filter is EntityFilter {
-  return filter.hasOwnProperty('anyOf');
-}
diff --git a/plugins/catalog-backend/src/service/NextEntitiesCatalog.test.ts b/plugins/catalog-backend/src/service/NextEntitiesCatalog.test.ts
index 0c805e1b17..32d5fa843e 100644
--- a/plugins/catalog-backend/src/service/NextEntitiesCatalog.test.ts
+++ b/plugins/catalog-backend/src/service/NextEntitiesCatalog.test.ts
@@ -284,9 +284,7 @@ describe('NextEntitiesCatalog', () => {
           key: 'spec.test',
           matchValueExists: true,
         };
-        const request = {
-          filter: { anyOf: [{ allOf: [testFilter] }] },
-        };
+        const request = { filter: testFilter };
         const { entities } = await catalog.entities(request);
 
         expect(entities.length).toBe(1);
@@ -344,14 +342,10 @@ describe('NextEntitiesCatalog', () => {
         };
         const request = {
           filter: {
-            anyOf: [
+            allOf: [
+              testFilter1,
               {
-                allOf: [
-                  testFilter1,
-                  {
-                    anyOf: [{ allOf: [testFilter2] }, { allOf: [testFilter3] }],
-                  },
-                ],
+                anyOf: [testFilter2, testFilter3],
               },
             ],
           },
diff --git a/plugins/catalog-backend/src/service/NextEntitiesCatalog.ts b/plugins/catalog-backend/src/service/NextEntitiesCatalog.ts
index 52d6ed1bdd..841e57c921 100644
--- a/plugins/catalog-backend/src/service/NextEntitiesCatalog.ts
+++ b/plugins/catalog-backend/src/service/NextEntitiesCatalog.ts
@@ -107,30 +107,56 @@ function addCondition(
   );
 }
 
-function isEntityFilter(
+function isEntitiesSearchFilter(
   filter: EntitiesSearchFilter | EntityFilter,
-): filter is EntityFilter {
+): filter is EntitiesSearchFilter {
+  return filter.hasOwnProperty('key');
+}
+
+function isAndEntityFilter(
+  filter: { allOf: EntityFilter[] } | EntityFilter,
+): filter is { allOf: EntityFilter[] } {
+  return filter.hasOwnProperty('allOf');
+}
+
+function isOrEntityFilter(
+  filter: { anyOf: EntityFilter[] } | EntityFilter,
+): filter is { anyOf: EntityFilter[] } {
   return filter.hasOwnProperty('anyOf');
 }
 
 function parseFilter(
-  filters: EntityFilter,
+  filter: EntityFilter,
   query: Knex.QueryBuilder,
   db: Knex,
 ): Knex.QueryBuilder {
-  let cumulativeQuery = query;
-  for (const singleFilter of filters?.anyOf ?? []) {
-    cumulativeQuery = cumulativeQuery.orWhere(function singleFilterFn() {
-      for (const filter of singleFilter.allOf) {
-        if (isEntityFilter(filter)) {
-          this.andWhere(subQuery => parseFilter(filter, subQuery, db));
-        } else {
-          addCondition(this, db, filter);
-        }
-      }
+  if (isEntitiesSearchFilter(filter)) {
+    return query.where(function filterFunction() {
+      addCondition(this, db, filter);
     });
   }
-  return cumulativeQuery;
+
+  if (isOrEntityFilter(filter)) {
+    let cumulativeQuery = query;
+    for (const subFilter of filter.anyOf ?? []) {
+      cumulativeQuery = cumulativeQuery.orWhere(subQuery =>
+        parseFilter(subFilter, subQuery, db),
+      );
+    }
+    return cumulativeQuery;
+  }
+
+  if (isAndEntityFilter(filter)) {
+    let cumulativeQuery = query;
+    for (const subFilter of filter.allOf ?? []) {
+      cumulativeQuery = cumulativeQuery.andWhere(subQuery =>
+        parseFilter(subFilter, subQuery, db),
+      );
+    }
+    return cumulativeQuery;
+  }
+
+  return query;
 }
 
 export class NextEntitiesCatalog implements EntitiesCatalog {