diff --git a/plugins/node/instrumentation-undici/src/undici.ts b/plugins/node/instrumentation-undici/src/undici.ts
index 1d5445d60b..0d8ebedc73 100644
--- a/plugins/node/instrumentation-undici/src/undici.ts
+++ b/plugins/node/instrumentation-undici/src/undici.ts
@@ -68,7 +68,6 @@ export class UndiciInstrumentation extends InstrumentationBase<UndiciInstrumenta
   private _httpClientDurationHistogram!: Histogram;
   constructor(config: UndiciInstrumentationConfig = {}) {
     super(PACKAGE_NAME, PACKAGE_VERSION, config);
-    this.setConfig(config);
   }
 
   // No need to instrument files/modules
@@ -77,26 +76,32 @@ export class UndiciInstrumentation extends InstrumentationBase<UndiciInstrumenta
   }
 
   override disable(): void {
-    if (!this.getConfig().enabled) {
-      return;
-    }
-
+    super.disable();
     this._channelSubs.forEach(sub => sub.channel.unsubscribe(sub.onMessage));
     this._channelSubs.length = 0;
-    super.disable();
-    this.setConfig({ ...this.getConfig(), enabled: false });
   }
 
   override enable(): void {
-    if (this.getConfig().enabled) {
-      return;
-    }
+    // "enabled" handling is currently a bit messy with InstrumentationBase.
+    // If constructed with `{enabled: false}`, this `.enable()` is still called,
+    // and `this.getConfig().enabled !== this.isEnabled()`, creating confusion.
+    //
+    // For now, this class will setup for instrumenting if `.enable()` is
+    // called, but use `this.getConfig().enabled` to determine if
+    // instrumentation should be generated. This covers the more likely common
+    // case of config being given a construction time, rather than later via
+    // `instance.enable()`, `.disable()`, or `.setConfig()` calls.
     super.enable();
-    this.setConfig({ ...this.getConfig(), enabled: true });
 
-    // This method is called by the `InstrumentationAbstract` constructor before
-    // ours is called. So we need to ensure the property is initalized
+    // This method is called by the super-class constructor before ours is
+    // called. So we need to ensure the property is initalized.
     this._channelSubs = this._channelSubs || [];
+
+    // Avoid to duplicate subscriptions
+    if (this._channelSubs.length > 0) {
+      return;
+    }
+
     this.subscribeToChannel(
       'undici:request:create',
       this.onRequestCreated.bind(this)
@@ -113,16 +118,6 @@ export class UndiciInstrumentation extends InstrumentationBase<UndiciInstrumenta
     this.subscribeToChannel('undici:request:error', this.onError.bind(this));
   }
 
-  override setConfig(config: UndiciInstrumentationConfig = {}): void {
-    super.setConfig(config);
-
-    if (config?.enabled) {
-      this.enable();
-    } else {
-      this.disable();
-    }
-  }
-
   protected override _updateMetricInstruments() {
     this._httpClientDurationHistogram = this.meter.createHistogram(
       'http.client.request.duration',
@@ -162,9 +157,10 @@ export class UndiciInstrumentation extends InstrumentationBase<UndiciInstrumenta
     // - ignored by config
     // - method is 'CONNECT'
     const config = this.getConfig();
+    const enabled = config.enabled !== false;
     const shouldIgnoreReq = safeExecuteInTheMiddle(
       () =>
-        !config.enabled ||
+        !enabled ||
         request.method === 'CONNECT' ||
         config.ignoreRequestHook?.(request),
       e => e && this._diag.error('caught ignoreRequestHook error: ', e),
diff --git a/plugins/node/instrumentation-undici/test/fetch.test.ts b/plugins/node/instrumentation-undici/test/fetch.test.ts
index fc369edead..9ef4e90767 100644
--- a/plugins/node/instrumentation-undici/test/fetch.test.ts
+++ b/plugins/node/instrumentation-undici/test/fetch.test.ts
@@ -35,19 +35,16 @@ import { MockPropagation } from './utils/mock-propagation';
 import { MockServer } from './utils/mock-server';
 import { assertSpan } from './utils/assertSpan';
 
-const instrumentation = new UndiciInstrumentation();
-instrumentation.enable();
-instrumentation.disable();
-
-const protocol = 'http';
-const hostname = 'localhost';
-const mockServer = new MockServer();
-const memoryExporter = new InMemorySpanExporter();
-const provider = new NodeTracerProvider();
-provider.addSpanProcessor(new SimpleSpanProcessor(memoryExporter));
-instrumentation.setTracerProvider(provider);
-
 describe('UndiciInstrumentation `fetch` tests', function () {
+  let instrumentation: UndiciInstrumentation;
+
+  const protocol = 'http';
+  const hostname = 'localhost';
+  const mockServer = new MockServer();
+  const memoryExporter = new InMemorySpanExporter();
+  const provider = new NodeTracerProvider();
+  provider.addSpanProcessor(new SimpleSpanProcessor(memoryExporter));
+
   before(function (done) {
     // Do not test if the `fetch` global API is not available
     // This applies to nodejs < v18 or nodejs < v16.15 wihtout the flag
@@ -57,6 +54,9 @@ describe('UndiciInstrumentation `fetch` tests', function () {
       this.skip();
     }
 
+    instrumentation = new UndiciInstrumentation();
+    instrumentation.setTracerProvider(provider);
+
     propagation.setGlobalPropagator(new MockPropagation());
     context.setGlobalContextManager(new AsyncHooksContextManager().enable());
     mockServer.start(done);
@@ -105,8 +105,8 @@ describe('UndiciInstrumentation `fetch` tests', function () {
       let spans = memoryExporter.getFinishedSpans();
       assert.strictEqual(spans.length, 0);
 
-      // Disable via config
-      instrumentation.setConfig({ enabled: false });
+      // Disable
+      instrumentation.disable();
 
       const fetchUrl = `${protocol}://${hostname}:${mockServer.port}/?query=test`;
       const response = await fetch(fetchUrl);
@@ -126,7 +126,8 @@ describe('UndiciInstrumentation `fetch` tests', function () {
     });
     afterEach(function () {
       // Empty configuration & disable
-      instrumentation.setConfig({ enabled: false });
+      instrumentation.setConfig({});
+      instrumentation.disable();
     });
 
     it('should create valid spans even if the configuration hooks fail', async function () {
@@ -135,7 +136,6 @@ describe('UndiciInstrumentation `fetch` tests', function () {
 
       // Set the bad configuration
       instrumentation.setConfig({
-        enabled: true,
         ignoreRequestHook: () => {
           throw new Error('ignoreRequestHook error');
         },
@@ -204,7 +204,6 @@ describe('UndiciInstrumentation `fetch` tests', function () {
 
       // Set configuration
       instrumentation.setConfig({
-        enabled: true,
         ignoreRequestHook: req => {
           return req.path.indexOf('/ignore/path') !== -1;
         },
@@ -302,7 +301,6 @@ describe('UndiciInstrumentation `fetch` tests', function () {
       assert.strictEqual(spans.length, 0);
 
       instrumentation.setConfig({
-        enabled: true,
         requireParentforSpans: true,
       });
 
@@ -322,7 +320,6 @@ describe('UndiciInstrumentation `fetch` tests', function () {
       assert.strictEqual(spans.length, 0);
 
       instrumentation.setConfig({
-        enabled: true,
         requireParentforSpans: true,
       });
 
diff --git a/plugins/node/instrumentation-undici/test/metrics.test.ts b/plugins/node/instrumentation-undici/test/metrics.test.ts
index 0fc633ef19..a903698385 100644
--- a/plugins/node/instrumentation-undici/test/metrics.test.ts
+++ b/plugins/node/instrumentation-undici/test/metrics.test.ts
@@ -31,24 +31,19 @@ import { MockServer } from './utils/mock-server';
 import { MockMetricsReader } from './utils/mock-metrics-reader';
 import { SemanticAttributes } from '../src/enums/SemanticAttributes';
 
-const instrumentation = new UndiciInstrumentation();
-instrumentation.enable();
-instrumentation.disable();
-
-const protocol = 'http';
-const hostname = 'localhost';
-const mockServer = new MockServer();
-const provider = new NodeTracerProvider();
-const meterProvider = new MeterProvider();
-const metricsMemoryExporter = new InMemoryMetricExporter(
-  AggregationTemporality.DELTA
-);
-const metricReader = new MockMetricsReader(metricsMemoryExporter);
-meterProvider.addMetricReader(metricReader);
-instrumentation.setTracerProvider(provider);
-instrumentation.setMeterProvider(meterProvider);
-
 describe('UndiciInstrumentation metrics tests', function () {
+  let instrumentation: UndiciInstrumentation;
+  const protocol = 'http';
+  const hostname = 'localhost';
+  const mockServer = new MockServer();
+  const provider = new NodeTracerProvider();
+  const meterProvider = new MeterProvider();
+  const metricsMemoryExporter = new InMemoryMetricExporter(
+    AggregationTemporality.DELTA
+  );
+  const metricReader = new MockMetricsReader(metricsMemoryExporter);
+  meterProvider.addMetricReader(metricReader);
+
   before(function (done) {
     // Do not test if the `fetch` global API is not available
     // This applies to nodejs < v18 or nodejs < v16.15 without the flag
@@ -58,6 +53,10 @@ describe('UndiciInstrumentation metrics tests', function () {
       this.skip();
     }
 
+    instrumentation = new UndiciInstrumentation();
+    instrumentation.setTracerProvider(provider);
+    instrumentation.setMeterProvider(meterProvider);
+
     context.setGlobalContextManager(new AsyncHooksContextManager().enable());
     mockServer.start(done);
     mockServer.mockListener((req, res) => {
@@ -67,13 +66,10 @@ describe('UndiciInstrumentation metrics tests', function () {
       res.write(JSON.stringify({ success: true }));
       res.end();
     });
-
-    // enable instrumentation for all tests
-    instrumentation.enable();
   });
 
   after(function (done) {
-    instrumentation.disable();
+    instrumentation?.disable();
     context.disable();
     propagation.disable();
     mockServer.mockListener(undefined);
diff --git a/plugins/node/instrumentation-undici/test/undici.test.ts b/plugins/node/instrumentation-undici/test/undici.test.ts
index b0bd088199..451bb71f3f 100644
--- a/plugins/node/instrumentation-undici/test/undici.test.ts
+++ b/plugins/node/instrumentation-undici/test/undici.test.ts
@@ -39,26 +39,6 @@ import { assertSpan } from './utils/assertSpan';
 
 import type { fetch, stream, request, Client, Dispatcher } from 'undici';
 
-const instrumentation = new UndiciInstrumentation();
-instrumentation.enable();
-instrumentation.disable();
-
-// Reference to the `undici` module
-let undici: {
-  fetch: typeof fetch;
-  request: typeof request;
-  stream: typeof stream;
-  Client: typeof Client;
-};
-
-const protocol = 'http';
-const hostname = 'localhost';
-const mockServer = new MockServer();
-const memoryExporter = new InMemorySpanExporter();
-const provider = new NodeTracerProvider();
-provider.addSpanProcessor(new SimpleSpanProcessor(memoryExporter));
-instrumentation.setTracerProvider(provider);
-
 // Undici docs (https://github.com/nodejs/undici#garbage-collection) suggest
 // that an undici response body should always be consumed.
 async function consumeResponseBody(body: Dispatcher.ResponseData['body']) {
@@ -74,6 +54,23 @@ async function consumeResponseBody(body: Dispatcher.ResponseData['body']) {
 }
 
 describe('UndiciInstrumentation `undici` tests', function () {
+  let instrumentation: UndiciInstrumentation;
+
+  // Reference to the `undici` module
+  let undici: {
+    fetch: typeof fetch;
+    request: typeof request;
+    stream: typeof stream;
+    Client: typeof Client;
+  };
+
+  const protocol = 'http';
+  const hostname = 'localhost';
+  const mockServer = new MockServer();
+  const memoryExporter = new InMemorySpanExporter();
+  const provider = new NodeTracerProvider();
+  provider.addSpanProcessor(new SimpleSpanProcessor(memoryExporter));
+
   before(function (done) {
     // Load `undici`. It may fail if nodejs version is <18 because the module uses
     // features only available from that version. In that case skip the test.
@@ -83,6 +80,9 @@ describe('UndiciInstrumentation `undici` tests', function () {
       this.skip();
     }
 
+    instrumentation = new UndiciInstrumentation();
+    instrumentation.setTracerProvider(provider);
+
     propagation.setGlobalPropagator(new MockPropagation());
     context.setGlobalContextManager(new AsyncHooksContextManager().enable());
     mockServer.start(done);
@@ -136,7 +136,7 @@ describe('UndiciInstrumentation `undici` tests', function () {
       assert.strictEqual(spans.length, 0);
 
       // Disable via config
-      instrumentation.setConfig({ enabled: false });
+      instrumentation.disable();
 
       const requestUrl = `${protocol}://${hostname}:${mockServer.port}/?query=test`;
       const { headers, body } = await undici.request(requestUrl);
@@ -157,7 +157,6 @@ describe('UndiciInstrumentation `undici` tests', function () {
       instrumentation.enable();
       // Set configuration
       instrumentation.setConfig({
-        enabled: true,
         ignoreRequestHook: req => {
           return req.path.indexOf('/ignore/path') !== -1;
         },
@@ -188,7 +187,8 @@ describe('UndiciInstrumentation `undici` tests', function () {
     });
     afterEach(function () {
       // Empty configuration & disable
-      instrumentation.setConfig({ enabled: false });
+      instrumentation.setConfig({});
+      instrumentation.disable();
     });
 
     it('should ignore requests based on the result of ignoreRequestHook', async function () {
@@ -595,7 +595,6 @@ describe('UndiciInstrumentation `undici` tests', function () {
 
       // Set the bad configuration
       instrumentation.setConfig({
-        enabled: true,
         ignoreRequestHook: () => {
           throw new Error('ignoreRequestHook error');
         },
@@ -639,7 +638,6 @@ describe('UndiciInstrumentation `undici` tests', function () {
       assert.strictEqual(spans.length, 0);
 
       instrumentation.setConfig({
-        enabled: true,
         requireParentforSpans: true,
       });
 
@@ -661,7 +659,6 @@ describe('UndiciInstrumentation `undici` tests', function () {
       assert.strictEqual(spans.length, 0);
 
       instrumentation.setConfig({
-        enabled: true,
         requireParentforSpans: true,
       });
 
@@ -685,7 +682,6 @@ describe('UndiciInstrumentation `undici` tests', function () {
       assert.strictEqual(spans.length, 0);
 
       instrumentation.setConfig({
-        enabled: true,
         requireParentforSpans: true,
       });