diff --git a/.changeset/green-cooks-sort.md b/.changeset/green-cooks-sort.md
new file mode 100644
index 0000000000000..51dd86ac2e567
--- /dev/null
+++ b/.changeset/green-cooks-sort.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog': minor
+---
+
+Adding negation keyword for entity filtering
diff --git a/plugins/catalog/src/alpha/filter/parseFilterExpression.test.ts b/plugins/catalog/src/alpha/filter/parseFilterExpression.test.ts
index 616091739e1a3..eda5def76ede6 100644
--- a/plugins/catalog/src/alpha/filter/parseFilterExpression.test.ts
+++ b/plugins/catalog/src/alpha/filter/parseFilterExpression.test.ts
@@ -93,6 +93,20 @@ describe('parseFilterExpression', () => {
     );
   });
 
+  it('recognizes negation key', () => {
+    const component = { kind: 'Component' } as unknown as Entity;
+    expect(run('not:kind:user')(component)).toBe(true);
+  });
+
+  it('supports negation and affirmative expressions', () => {
+    const component = {
+      kind: 'Component',
+      spec: { type: 'service' },
+    } as unknown as Entity;
+    expect(run('not:kind:user type:service')(component)).toBe(true);
+    expect(run('type:service not:kind:user')(component)).toBe(true);
+  });
+
   it('rejects unknown keys', () => {
     expect(() => run('unknown:foo')).toThrowErrorMatchingInlineSnapshot(
       `"'unknown' is not a valid filter expression key, expected one of 'kind','type','is','has'"`,
@@ -123,17 +137,25 @@ describe('splitFilterExpression', () => {
     expect(run('')).toEqual([]);
     expect(run('   ')).toEqual([]);
     expect(run('kind:component')).toEqual([
-      { key: 'kind', parameters: ['component'] },
+      { key: 'kind', parameters: ['component'], negation: false },
     ]);
     expect(run('kind:component,user')).toEqual([
-      { key: 'kind', parameters: ['component', 'user'] },
+      { key: 'kind', parameters: ['component', 'user'], negation: false },
+    ]);
+    expect(run('kind:component,user not:type:foo')).toEqual([
+      { key: 'kind', parameters: ['component', 'user'], negation: false },
+      { key: 'type', parameters: ['foo'], negation: true },
+    ]);
+    expect(run('not:type:foo kind:component,user')).toEqual([
+      { key: 'type', parameters: ['foo'], negation: true },
+      { key: 'kind', parameters: ['component', 'user'], negation: false },
     ]);
     expect(run('kind:component,user type:foo')).toEqual([
-      { key: 'kind', parameters: ['component', 'user'] },
-      { key: 'type', parameters: ['foo'] },
+      { key: 'kind', parameters: ['component', 'user'], negation: false },
+      { key: 'type', parameters: ['foo'], negation: false },
     ]);
     expect(run('with:multiple:colons')).toEqual([
-      { key: 'with', parameters: ['multiple:colons'] },
+      { key: 'with', parameters: ['multiple:colons'], negation: false },
     ]);
   });
 
diff --git a/plugins/catalog/src/alpha/filter/parseFilterExpression.ts b/plugins/catalog/src/alpha/filter/parseFilterExpression.ts
index 4f809690f713c..9775f16e51e03 100644
--- a/plugins/catalog/src/alpha/filter/parseFilterExpression.ts
+++ b/plugins/catalog/src/alpha/filter/parseFilterExpression.ts
@@ -27,6 +27,7 @@ const rootMatcherFactories: Record<
   (
     parameters: string[],
     onParseError: (error: Error) => void,
+    negation?: boolean,
   ) => EntityMatcherFn
 > = {
   kind: createKindMatcher,
@@ -60,9 +61,9 @@ export function parseFilterExpression(expression: string): {
   const parts = splitFilterExpression(expression, e =>
     expressionParseErrors.push(e),
   );
-
   const matchers = parts.flatMap(part => {
     const factory = rootMatcherFactories[part.key];
+    const negation = part.negation;
     if (!factory) {
       const known = Object.keys(rootMatcherFactories).map(m => `'${m}'`);
       expressionParseErrors.push(
@@ -76,7 +77,8 @@ export function parseFilterExpression(expression: string): {
     const matcher = factory(part.parameters, e =>
       expressionParseErrors.push(e),
     );
-    return [matcher];
+
+    return [negation ? (entity: Entity) => !matcher(entity) : matcher];
   });
 
   const filterFn = (entity: Entity) =>
@@ -97,16 +99,20 @@ export function parseFilterExpression(expression: string): {
 export function splitFilterExpression(
   expression: string,
   onParseError: (error: Error) => void,
-): Array<{ key: string; parameters: string[] }> {
+): Array<{ key: string; parameters: string[]; negation: boolean }> {
   const words = expression
     .split(' ')
     .map(w => w.trim())
     .filter(Boolean);
 
-  const result = new Array<{ key: string; parameters: string[] }>();
+  const result = new Array<{
+    key: string;
+    parameters: string[];
+    negation: boolean;
+  }>();
 
   for (const word of words) {
-    const match = word.match(/^([^:]+):(.+)$/);
+    const match = word.match(/^(not:)?([^:]+):(.+)$/);
     if (!match) {
       onParseError(
         new InputError(
@@ -115,11 +121,10 @@ export function splitFilterExpression(
       );
       continue;
     }
-
-    const key = match[1];
-    const parameters = match[2].split(',').filter(Boolean); // silently ignore double commas
-
-    result.push({ key, parameters });
+    const key = match[2];
+    const parameters = match[3].split(',').filter(Boolean); // silently ignore double commas
+    const negation = Boolean(match[1]);
+    result.push({ key, parameters, negation });
   }
 
   return result;