diff --git a/CHANGELOG.asciidoc b/CHANGELOG.asciidoc
index a93ffef990f..a1192836ee9 100644
--- a/CHANGELOG.asciidoc
+++ b/CHANGELOG.asciidoc
@@ -65,6 +65,8 @@ Notes:
   and the APM agent will automatically add a MetricReader to ship metrics to
   APM server. See the <<opentelemetry-bridge>> for details. ({pull}3152[#3152])
 
+* Add `apm.setGlobalLabel()` to dynamically extend the `globalLabels` set in the initial config. Refer to <<apm-set-global-label>> for details. ({pull}3337[#3337])
+
 [float]
 ===== Chores
 
diff --git a/docs/agent-api.asciidoc b/docs/agent-api.asciidoc
index fae5fd4751b..ddcbed51340 100644
--- a/docs/agent-api.asciidoc
+++ b/docs/agent-api.asciidoc
@@ -291,6 +291,25 @@ WARNING: Avoid defining too many user-specified labels.
 Defining too many unique fields in an index is a condition that can lead to a
 {ref}/mapping.html#mapping-limit-settings[mapping explosion].
 
+[[apm-set-global-label]]
+==== `apm.setGlobalLabel(name, value)`
+
+[small]#Added in: REPLACEME#
+
+* `name` +{type-string}+
+* `value` +{type-string}+ | +{type-number}+ | +{type-boolean}+
+
+Extends the <<global-labels>> configuration. It allows setting labels that are applied to all transactions. A potential use case is to specify a label with the state of your application: `'initializing' | 'available' | 'unhealthy'`.
+
+TIP: Labels are key/value pairs that are indexed by Elasticsearch and therefore searchable
+(as opposed to data set via <<apm-set-custom-context,`apm.setCustomContext()`>>).
+Before using custom labels, ensure you understand the different types of
+{apm-guide-ref}/metadata.html[metadata] that are available.
+
+WARNING: Avoid defining too many user-specified labels.
+Defining too many unique fields in an index is a condition that can lead to a
+{ref}/mapping.html#mapping-limit-settings[mapping explosion].
+
 [[apm-capture-error]]
 ==== `apm.captureError(error[, options][, callback])`
 
diff --git a/index.d.ts b/index.d.ts
index a67ed7aaf75..b3614ca4233 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -116,6 +116,7 @@ declare namespace apm {
     currentSpan: Span | null;
 
     // Context
+    setGlobalLabel (name: string, value: LabelValue): void;
     setLabel (name: string, value: LabelValue, stringify?: boolean): boolean;
     addLabels (labels: Labels, stringify?: boolean): boolean;
     setUserContext (user: UserObject): void;
diff --git a/lib/agent.js b/lib/agent.js
index 8cd293aa8fc..33596ab4f02 100644
--- a/lib/agent.js
+++ b/lib/agent.js
@@ -355,6 +355,22 @@ Agent.prototype.setCustomContext = function (context) {
   return true
 }
 
+Agent.prototype.setGlobalLabel = function (key, value) {
+  if (!this._conf.globalLabels) this._conf.globalLabels = []
+  const foundPos = this._conf.globalLabels.findIndex(([name]) => key === name)
+  if (foundPos > -1) {
+    this._conf.globalLabels[foundPos][1] = value
+  } else {
+    this._conf.globalLabels.push([key, value])
+  }
+  this._transport.config({
+    globalLabels: this._conf.globalLabels.reduce((acc, [k, v]) => {
+      acc[k] = v
+      return acc
+    }, {})
+  })
+}
+
 Agent.prototype.setLabel = function (key, value, stringify) {
   var trans = this._instrumentation.currTransaction()
   if (!trans) return false
diff --git a/test/agent.test.js b/test/agent.test.js
index 523bc598ff6..4a1f85ec2e1 100644
--- a/test/agent.test.js
+++ b/test/agent.test.js
@@ -502,6 +502,80 @@ test('#setCustomContext()', function (t) {
   t.end()
 })
 
+test('#setGlobalLabel()', function (suite) {
+  let apmServer
+  let suiteAgentOpts
+
+  suite.test('setup mock APM server', function (t) {
+    apmServer = new MockAPMServer()
+    apmServer.start(function (serverUrl) {
+      t.comment('mock APM serverUrl: ' + serverUrl)
+      suiteAgentOpts = Object.assign(
+        {},
+        agentOpts,
+        { serverUrl }
+      )
+      t.end()
+    })
+  })
+
+  suite.test('sets a global label', async function (t) {
+    apmServer.clear()
+    const agent = new Agent().start(suiteAgentOpts)
+    agent.setGlobalLabel('goo', 1)
+    t.deepEqual(agent._conf.globalLabels, Object.entries({ goo: 1 }), 'agent._conf.globalLabels')
+    agent.startTransaction('manual')
+    agent.endTransaction()
+    await agent.flush()
+    t.deepEqual(apmServer.events[0].metadata.labels, { goo: 1 }, 'APM server metadata.labels')
+    agent.destroy()
+    t.end()
+  })
+
+  suite.test('extends the predefined global labels', async function (t) {
+    apmServer.clear()
+    const agentOptsWithGlobalLabels = Object.assign(
+      {},
+      suiteAgentOpts,
+      { globalLabels: { some: true } }
+    )
+    const agent = new Agent().start(agentOptsWithGlobalLabels)
+    agent.setGlobalLabel('goo', 1)
+    t.deepEqual(agent._conf.globalLabels, Object.entries({ some: true, goo: 1 }), 'agent._conf.globalLabels')
+    agent.startTransaction('manual')
+    agent.endTransaction()
+    await agent.flush()
+    t.deepEqual(apmServer.events[0].metadata.labels, { some: true, goo: 1 }, 'APM server metadata.labels')
+    agent.destroy()
+    t.end()
+  })
+
+  suite.test('overrides an existing global label', async function (t) {
+    apmServer.clear()
+    const agentOptsWithGlobalLabels = Object.assign(
+      {},
+      suiteAgentOpts,
+      { globalLabels: { some: true, goo: 0 } }
+    )
+    const agent = new Agent().start(agentOptsWithGlobalLabels)
+    agent.setGlobalLabel('goo', 1)
+    t.deepEqual(agent._conf.globalLabels, Object.entries({ some: true, goo: 1 }), 'agent._conf.globalLabels')
+    agent.startTransaction('manual')
+    agent.endTransaction()
+    await agent.flush()
+    t.deepEqual(apmServer.events[0].metadata.labels, { some: true, goo: 1 }, 'APM server metadata.labels')
+    agent.destroy()
+    t.end()
+  })
+
+  suite.test('teardown mock APM server', function (t) {
+    apmServer.close()
+    t.end()
+  })
+
+  suite.end()
+})
+
 test('#setLabel()', function (t) {
   t.test('no active transaction', function (t) {
     const agent = new Agent().start(agentOptsNoopTransport)