diff --git a/docs/generated/devkit/NxJsonConfiguration.md b/docs/generated/devkit/NxJsonConfiguration.md
index e1752312e17aff..43e1bcc493fc54 100644
--- a/docs/generated/devkit/NxJsonConfiguration.md
+++ b/docs/generated/devkit/NxJsonConfiguration.md
@@ -19,6 +19,7 @@ Nx.json configuration
 ### Properties
 
 - [affected](../../devkit/documents/NxJsonConfiguration#affected): NxAffectedConfig
+- [base](../../devkit/documents/NxJsonConfiguration#base): string
 - [cacheDirectory](../../devkit/documents/NxJsonConfiguration#cachedirectory): string
 - [cli](../../devkit/documents/NxJsonConfiguration#cli): Object
 - [defaultProject](../../devkit/documents/NxJsonConfiguration#defaultproject): string
@@ -49,6 +50,14 @@ Default options for `nx affected`
 
 ---
 
+### base
+
+• `Optional` **base**: `string`
+
+Default value for --base used by `nx affected` and `nx format`.
+
+---
+
 ### cacheDirectory
 
 • `Optional` **cacheDirectory**: `string`
diff --git a/docs/generated/devkit/Workspace.md b/docs/generated/devkit/Workspace.md
index 989510615dc9bd..0790ff10f19216 100644
--- a/docs/generated/devkit/Workspace.md
+++ b/docs/generated/devkit/Workspace.md
@@ -17,6 +17,7 @@ use ProjectsConfigurations or NxJsonConfiguration
 ### Properties
 
 - [affected](../../devkit/documents/Workspace#affected): NxAffectedConfig
+- [base](../../devkit/documents/Workspace#base): string
 - [cacheDirectory](../../devkit/documents/Workspace#cachedirectory): string
 - [cli](../../devkit/documents/Workspace#cli): Object
 - [defaultProject](../../devkit/documents/Workspace#defaultproject): string
@@ -53,6 +54,18 @@ Default options for `nx affected`
 
 ---
 
+### base
+
+• `Optional` **base**: `string`
+
+Default value for --base used by `nx affected` and `nx format`.
+
+#### Inherited from
+
+[NxJsonConfiguration](../../devkit/documents/NxJsonConfiguration).[base](../../devkit/documents/NxJsonConfiguration#base)
+
+---
+
 ### cacheDirectory
 
 • `Optional` **cacheDirectory**: `string`
diff --git a/docs/shared/reference/nx-json.md b/docs/shared/reference/nx-json.md
index 8dc972d55b6831..8c3d9cf2167f95 100644
--- a/docs/shared/reference/nx-json.md
+++ b/docs/shared/reference/nx-json.md
@@ -47,11 +47,9 @@ In Nx 16, if the `npmScope` property is present, it will be used as a prefix. If
 
 In Nx 17, the `npmScope` property is ignored.
 
-### Affected
+### Base
 
-Tells Nx which branch and HEAD to use when calculating affected projects.
-
-- `defaultBase` defines the default base branch, defaulted to `main`.
+Tells Nx which branch and HEAD to use when calculating affected projects. Defaults to `main`.
 
 ### inputs & namedInputs
 
diff --git a/e2e/angular-core/src/ng-add.test.ts b/e2e/angular-core/src/ng-add.test.ts
index 31db4f3789e633..df10f89aea0a2b 100644
--- a/e2e/angular-core/src/ng-add.test.ts
+++ b/e2e/angular-core/src/ng-add.test.ts
@@ -141,9 +141,7 @@ describe('convert Angular CLI workspace to an Nx workspace', () => {
     // check nx.json
     const nxJson = readJson('nx.json');
     expect(nxJson).toEqual({
-      affected: {
-        defaultBase: 'main',
-      },
+      base: 'main',
       namedInputs: {
         default: ['{projectRoot}/**/*', 'sharedGlobals'],
         production: [
diff --git a/packages/angular/src/generators/ng-add/__snapshots__/migrate-from-angular-cli.spec.ts.snap b/packages/angular/src/generators/ng-add/__snapshots__/migrate-from-angular-cli.spec.ts.snap
index 86f37c16528e0b..c928863b0ab1f7 100644
--- a/packages/angular/src/generators/ng-add/__snapshots__/migrate-from-angular-cli.spec.ts.snap
+++ b/packages/angular/src/generators/ng-add/__snapshots__/migrate-from-angular-cli.spec.ts.snap
@@ -80,9 +80,7 @@ exports[`workspace move to nx layout should create a root eslint config 1`] = `
 
 exports[`workspace move to nx layout should create nx.json 1`] = `
 {
-  "affected": {
-    "defaultBase": "main",
-  },
+  "base": "main",
   "defaultProject": "myApp",
   "namedInputs": {
     "default": [
diff --git a/packages/angular/src/generators/ng-add/utilities/workspace.ts b/packages/angular/src/generators/ng-add/utilities/workspace.ts
index 1248088cf799f7..0abc6b6745ba6e 100644
--- a/packages/angular/src/generators/ng-add/utilities/workspace.ts
+++ b/packages/angular/src/generators/ng-add/utilities/workspace.ts
@@ -49,9 +49,7 @@ export function createNxJson(
   const targets = getWorkspaceCommonTargets(tree);
 
   writeJson<NxJsonConfiguration>(tree, 'nx.json', {
-    affected: {
-      defaultBase: options.defaultBase ?? deduceDefaultBase(),
-    },
+    base: options.defaultBase ?? deduceDefaultBase(),
     namedInputs: {
       sharedGlobals: [],
       default: ['{projectRoot}/**/*', 'sharedGlobals'],
diff --git a/packages/nx/migrations.json b/packages/nx/migrations.json
index bea9737741c84f..c579dec4ca274e 100644
--- a/packages/nx/migrations.json
+++ b/packages/nx/migrations.json
@@ -76,6 +76,11 @@
       "version": "17.0.0-rc.1",
       "description": "Migration for v17.0.0-rc.1",
       "implementation": "./src/migrations/update-17-0-0/rm-default-collection-npm-scope"
+    },
+    "update-17.1.0": {
+      "version": "17.1.0",
+      "description": "Moves affected.defaultBase to base in `nx.json`",
+      "implementation": "./src/migrations/update-17-1-0/move-default-base"
     }
   }
 }
diff --git a/packages/nx/schemas/nx-schema.json b/packages/nx/schemas/nx-schema.json
index 1e3df3ecb154d9..76183ff0b0f9f8 100644
--- a/packages/nx/schemas/nx-schema.json
+++ b/packages/nx/schemas/nx-schema.json
@@ -18,7 +18,12 @@
           "description": "Default based branch used by affected commands."
         }
       },
-      "additionalProperties": false
+      "additionalProperties": false,
+      "deprecated": "Use `base` instead."
+    },
+    "base": {
+      "type": "string",
+      "description": "Default --base used by affected logic."
     },
     "tasksRunnerOptions": {
       "type": "object",
diff --git a/packages/nx/src/adapter/compat.ts b/packages/nx/src/adapter/compat.ts
index 4a122afa3c713f..fbfbc310a29f17 100644
--- a/packages/nx/src/adapter/compat.ts
+++ b/packages/nx/src/adapter/compat.ts
@@ -53,6 +53,7 @@ export const allowedProjectExtensions = [
 export const allowedWorkspaceExtensions = [
   'implicitDependencies',
   'affected',
+  'base',
   'tasksRunnerOptions',
   'workspaceLayout',
   'plugins',
diff --git a/packages/nx/src/command-line/init/implementation/utils.ts b/packages/nx/src/command-line/init/implementation/utils.ts
index 4502dfe30323eb..fbe8a65d30e784 100644
--- a/packages/nx/src/command-line/init/implementation/utils.ts
+++ b/packages/nx/src/command-line/init/implementation/utils.ts
@@ -76,8 +76,7 @@ export function createNxJsonFile(
     nxJson.targetDefaults[target].cache ??= true;
   }
 
-  nxJson.affected ??= {};
-  nxJson.affected.defaultBase ??= deduceDefaultBase();
+  nxJson.base ??= deduceDefaultBase();
   writeJsonFile(nxJsonPath, nxJson);
 }
 
diff --git a/packages/nx/src/config/nx-json.ts b/packages/nx/src/config/nx-json.ts
index eff7a9441f81d4..efa70482593a4d 100644
--- a/packages/nx/src/config/nx-json.ts
+++ b/packages/nx/src/config/nx-json.ts
@@ -183,6 +183,12 @@ export interface NxJsonConfiguration<T = '*' | string[]> {
    * Default options for `nx affected`
    */
   affected?: NxAffectedConfig;
+
+  /**
+   * Default value for --base used by `nx affected` and `nx format`.
+   */
+  base?: string;
+
   /**
    * Where new apps + libs should be placed
    */
diff --git a/packages/nx/src/migrations/update-17-1-0/move-default-base.spec.ts b/packages/nx/src/migrations/update-17-1-0/move-default-base.spec.ts
new file mode 100644
index 00000000000000..d8c7454e29c9ef
--- /dev/null
+++ b/packages/nx/src/migrations/update-17-1-0/move-default-base.spec.ts
@@ -0,0 +1,46 @@
+import { createTreeWithEmptyWorkspace } from 'nx/src/generators/testing-utils/create-tree-with-empty-workspace';
+import update from './move-default-base';
+import { Tree } from 'nx/src/generators/tree';
+import { readNxJson, updateNxJson } from 'nx/src/generators/utils/nx-json';
+
+describe('update-17.1.0 migration', () => {
+  let tree: Tree;
+
+  beforeEach(() => {
+    tree = createTreeWithEmptyWorkspace({ layout: 'apps-libs' });
+  });
+
+  it("shouldn't do anything if affected.defaultBase is not set", () => {
+    tree.write('nx.json', JSON.stringify({}));
+    update(tree);
+    expect(readNxJson(tree)).toEqual({});
+  });
+
+  it("shouldn't remove affected if other keys present", () => {
+    updateNxJson(tree, {
+      affected: {
+        defaultBase: 'master',
+        otherKey: 'otherValue',
+      } as any,
+    });
+    update(tree);
+    expect(readNxJson(tree)).toEqual({
+      affected: {
+        otherKey: 'otherValue',
+      },
+      base: 'master',
+    });
+  });
+
+  it('should remove affected if no other keys present', () => {
+    updateNxJson(tree, {
+      affected: {
+        defaultBase: 'master',
+      } as any,
+    });
+    update(tree);
+    expect(readNxJson(tree)).toEqual({
+      base: 'master',
+    });
+  });
+});
diff --git a/packages/nx/src/migrations/update-17-1-0/move-default-base.ts b/packages/nx/src/migrations/update-17-1-0/move-default-base.ts
new file mode 100644
index 00000000000000..312acc01ee931c
--- /dev/null
+++ b/packages/nx/src/migrations/update-17-1-0/move-default-base.ts
@@ -0,0 +1,18 @@
+/* eslint-disable @typescript-eslint/no-unused-vars */
+import { readNxJson, updateNxJson } from '../../generators/utils/nx-json';
+import { Tree } from '../../generators/tree';
+
+/**
+ * Updates existing workspaces to move nx.json's affected.defaultBase to nx.json's base.
+ */
+export default function update(host: Tree) {
+  const nxJson = readNxJson(host);
+  if (nxJson.affected?.defaultBase) {
+    nxJson.base = nxJson.affected.defaultBase;
+    delete nxJson.affected.defaultBase;
+    if (Object.keys(nxJson.affected).length === 0) {
+      delete nxJson.affected;
+    }
+    updateNxJson(host, nxJson);
+  }
+}
diff --git a/packages/nx/src/utils/command-line-utils.ts b/packages/nx/src/utils/command-line-utils.ts
index cc5a731c92cc17..1a4ff589b5b429 100644
--- a/packages/nx/src/utils/command-line-utils.ts
+++ b/packages/nx/src/utils/command-line-utils.ts
@@ -142,7 +142,7 @@ export function splitArgsIntoNxArgsAndOverrides(
     }
 
     if (!nxArgs.base) {
-      nxArgs.base = nxJson.affected?.defaultBase || 'main';
+      nxArgs.base = nxJson.base ?? nxJson.affected?.defaultBase ?? 'main';
 
       // No user-provided arguments to set the affected criteria, so inform the user of the defaults being used
       if (
diff --git a/packages/workspace/src/generators/ci-workflow/ci-workflow.spec.ts b/packages/workspace/src/generators/ci-workflow/ci-workflow.spec.ts
index b1c3cb24df6545..95c4d57da8836a 100644
--- a/packages/workspace/src/generators/ci-workflow/ci-workflow.spec.ts
+++ b/packages/workspace/src/generators/ci-workflow/ci-workflow.spec.ts
@@ -88,6 +88,21 @@ describe('CI Workflow generator', () => {
         );
       });
 
+      it('should prefix nx.json base with origin/ if ci is bitbucket-pipelines', async () => {
+        setNxCloud(tree);
+
+        const nxJson = readJson(tree, 'nx.json');
+        nxJson.base = 'my-branch';
+        writeJson(tree, 'nx.json', nxJson);
+
+        await ciWorkflowGenerator(tree, {
+          ci: 'bitbucket-pipelines',
+          name: 'CI',
+        });
+
+        expect(readJson(tree, 'nx.json').base).toEqual('origin/my-branch');
+      });
+
       it('should generate gitlab config', async () => {
         setNxCloud(tree);
         await ciWorkflowGenerator(tree, { ci: 'gitlab', name: 'CI' });
diff --git a/packages/workspace/src/generators/ci-workflow/ci-workflow.ts b/packages/workspace/src/generators/ci-workflow/ci-workflow.ts
index a2a9e59f500728..05a63e51f7cead 100644
--- a/packages/workspace/src/generators/ci-workflow/ci-workflow.ts
+++ b/packages/workspace/src/generators/ci-workflow/ci-workflow.ts
@@ -68,13 +68,11 @@ function defaultBranchNeedsOriginPrefix(nxJson: NxJsonConfiguration): boolean {
 }
 
 function appendOriginPrefix(nxJson: NxJsonConfiguration): NxJsonConfiguration {
-  return {
-    ...nxJson,
-    affected: {
-      ...(nxJson.affected ?? {}),
-      defaultBase: nxJson.affected?.defaultBase
-        ? `origin/${nxJson.affected.defaultBase}`
-        : 'origin/main',
-    },
-  };
+  if (nxJson?.affected?.defaultBase) {
+    nxJson.affected.defaultBase = `origin/${nxJson.affected.defaultBase}`;
+  }
+  if (nxJson.base || !nxJson.affected) {
+    nxJson.base = `origin/${nxJson.base ?? deduceDefaultBase()}`;
+  }
+  return nxJson;
 }
diff --git a/packages/workspace/src/generators/new/generate-workspace-files.ts b/packages/workspace/src/generators/new/generate-workspace-files.ts
index 9d6d16168190f2..445b3ec6ff7f30 100644
--- a/packages/workspace/src/generators/new/generate-workspace-files.ts
+++ b/packages/workspace/src/generators/new/generate-workspace-files.ts
@@ -64,9 +64,7 @@ function createNxJson(
 ) {
   const nxJson: NxJsonConfiguration & { $schema: string } = {
     $schema: './node_modules/nx/schemas/nx-schema.json',
-    affected: {
-      defaultBase,
-    },
+    base: defaultBase,
     targetDefaults: {
       build: {
         cache: true,
@@ -86,6 +84,7 @@ function createNxJson(
 
   if (defaultBase === 'main') {
     delete nxJson.affected;
+    delete nxJson.base;
   }
   if (preset !== Preset.NPM) {
     nxJson.namedInputs = {