diff --git a/modelwriter.go b/modelwriter.go
index 2d7d2825b..cef59c0eb 100644
--- a/modelwriter.go
+++ b/modelwriter.go
@@ -48,7 +48,7 @@ type modelWriter struct {
 // writeTransaction encodes tx as JSON to the buffer, and then resets tx.
 func (w *modelWriter) writeTransaction(tx *Transaction, td *TransactionData) {
 	var modelTx model.Transaction
-	w.buildModelTransaction(&modelTx, tx, td)
+	BuildModelTransaction(&modelTx, tx, td)
 	w.json.RawString(`{"transaction":`)
 	modelTx.MarshalFastJSON(&w.json)
 	w.json.RawByte('}')
@@ -103,39 +103,6 @@ func (w *modelWriter) writeMetrics(m *Metrics) {
 	m.reset()
 }
 
-func (w *modelWriter) buildModelTransaction(out *model.Transaction, tx *Transaction, td *TransactionData) {
-	out.ID = model.SpanID(tx.traceContext.Span)
-	out.TraceID = model.TraceID(tx.traceContext.Trace)
-	sampled := tx.traceContext.Options.Recorded()
-	if !sampled {
-		out.Sampled = &notSampled
-	}
-	if tx.traceContext.State.haveSampleRate {
-		out.SampleRate = &tx.traceContext.State.sampleRate
-	}
-
-	out.ParentID = model.SpanID(tx.parentID)
-	out.Name = truncateString(td.Name)
-	out.Type = truncateString(td.Type)
-	out.Result = truncateString(td.Result)
-	out.Outcome = normalizeOutcome(td.Outcome)
-	out.Timestamp = model.Time(td.timestamp.UTC())
-	out.Duration = td.Duration.Seconds() * 1000
-	out.SpanCount.Started = td.spansCreated
-	out.SpanCount.Dropped = td.spansDropped
-	out.OTel = td.Context.otel
-	for _, sl := range td.links {
-		out.Links = append(out.Links, model.SpanLink{TraceID: model.TraceID(sl.Trace), SpanID: model.SpanID(sl.Span)})
-	}
-	if dss := buildDroppedSpansStats(td.droppedSpansStats); len(dss) > 0 {
-		out.DroppedSpansStats = dss
-	}
-
-	if sampled {
-		out.Context = td.Context.build()
-	}
-}
-
 func (w *modelWriter) buildModelSpan(out *model.Span, span *Span, sd *SpanData) {
 	w.modelStacktrace = w.modelStacktrace[:0]
 	out.ID = model.SpanID(span.traceContext.Span)
@@ -258,6 +225,40 @@ func (w *modelWriter) buildModelError(out *model.Error, e *ErrorData) {
 	out.Culprit = truncateString(out.Culprit)
 }
 
+// BuildModelTransaction converts apm transaction to model transaction
+func BuildModelTransaction(out *model.Transaction, tx *Transaction, td *TransactionData) {
+	out.ID = model.SpanID(tx.traceContext.Span)
+	out.TraceID = model.TraceID(tx.traceContext.Trace)
+	sampled := tx.traceContext.Options.Recorded()
+	if !sampled {
+		out.Sampled = &notSampled
+	}
+	if tx.traceContext.State.haveSampleRate {
+		out.SampleRate = &tx.traceContext.State.sampleRate
+	}
+
+	out.ParentID = model.SpanID(tx.parentID)
+	out.Name = truncateString(td.Name)
+	out.Type = truncateString(td.Type)
+	out.Result = truncateString(td.Result)
+	out.Outcome = normalizeOutcome(td.Outcome)
+	out.Timestamp = model.Time(td.timestamp.UTC())
+	out.Duration = td.Duration.Seconds() * 1000
+	out.SpanCount.Started = td.spansCreated
+	out.SpanCount.Dropped = td.spansDropped
+	out.OTel = td.Context.otel
+	for _, sl := range td.links {
+		out.Links = append(out.Links, model.SpanLink{TraceID: model.TraceID(sl.Trace), SpanID: model.SpanID(sl.Span)})
+	}
+	if dss := buildDroppedSpansStats(td.droppedSpansStats); len(dss) > 0 {
+		out.DroppedSpansStats = dss
+	}
+
+	if sampled {
+		out.Context = td.Context.build()
+	}
+}
+
 func stacktraceCulprit(frames []model.StacktraceFrame) string {
 	for _, frame := range frames {
 		if !frame.LibraryFrame {
diff --git a/module/apmlambda/go.mod b/module/apmlambda/go.mod
index d149c0b7a..1cb8ca81a 100644
--- a/module/apmlambda/go.mod
+++ b/module/apmlambda/go.mod
@@ -3,6 +3,7 @@ module go.elastic.co/apm/module/apmlambda/v2
 require (
 	github.com/aws/aws-lambda-go v1.8.0
 	go.elastic.co/apm/v2 v2.2.0
+	go.elastic.co/fastjson v1.1.0
 )
 
 replace go.elastic.co/apm/v2 => ../..
diff --git a/module/apmlambda/lambda.go b/module/apmlambda/lambda.go
index 449a84640..7863d772c 100644
--- a/module/apmlambda/lambda.go
+++ b/module/apmlambda/lambda.go
@@ -18,8 +18,10 @@
 package apmlambda // import "go.elastic.co/apm/module/apmlambda/v2"
 
 import (
+	"bytes"
 	"log"
 	"net"
+	"net/http"
 	"net/rpc"
 	"os"
 	"unicode/utf8"
@@ -28,7 +30,9 @@ import (
 	"github.com/aws/aws-lambda-go/lambdacontext"
 
 	"go.elastic.co/apm/v2"
+	"go.elastic.co/apm/v2/model"
 	"go.elastic.co/apm/v2/stacktrace"
+	"go.elastic.co/fastjson"
 )
 
 const (
@@ -51,6 +55,10 @@ var (
 		Request         string `json:"request,omitempty"`
 		Response        string `json:"response,omitempty"`
 	}
+
+	jsonw fastjson.Writer
+
+	ignoreTxnRegistration bool
 )
 
 func init() {
@@ -72,6 +80,17 @@ func (f *Function) Ping(req *messages.PingRequest, response *messages.PingRespon
 	return f.client.Call("Function.Ping", req, response)
 }
 
+func createPartialTransactionJSON(apmTx *apm.Transaction, w *fastjson.Writer) error {
+	var tx model.Transaction
+	apm.BuildModelTransaction(&tx, apmTx, apmTx.TransactionData)
+	w.RawString(`{"transaction":`)
+	if err := tx.MarshalFastJSON(w); err != nil {
+		return err
+	}
+	w.RawByte('}')
+	return nil
+}
+
 // Invoke invokes the Lambda function. This is our main trace point.
 func (f *Function) Invoke(req *messages.InvokeRequest, response *messages.InvokeResponse) error {
 	tx := f.tracer.StartTransaction(lambdacontext.FunctionName, "function")
@@ -92,6 +111,30 @@ func (f *Function) Invoke(req *messages.InvokeRequest, response *messages.Invoke
 	lambdaContext.Request = formatPayload(req.Payload)
 	lambdaContext.Response = ""
 
+	if !ignoreTxnRegistration {
+		defer jsonw.Reset()
+		if err := createPartialTransactionJSON(tx, &jsonw); err != nil {
+			log.Printf("failed to create partial transaction for registration: %v", err)
+		} else {
+			resp, err := http.Post(
+				// TODO: @lahsivjar better way to get base URI
+				"http://localhost:8200/register/transaction",
+				"application/vnd.elastic.apm.transaction+json",
+				bytes.NewReader(jsonw.Bytes()),
+			)
+			// Don't attempt registration for next invocations if network
+			// error or the registration endpoint is not found.
+			if err != nil || resp.StatusCode == 404 {
+				ignoreTxnRegistration = true
+			}
+			if err != nil {
+				log.Printf("failed to register transaction, req failed with error: %v", err)
+			}
+			if resp.StatusCode/100 != 2 {
+				log.Printf("failed to register transaction, req failed with status code: %d", resp.StatusCode)
+			}
+		}
+	}
 	err := f.client.Call("Function.Invoke", req, response)
 	if err != nil {
 		e := f.tracer.NewError(err)
diff --git a/module/apmlambda/lambda_test.go b/module/apmlambda/lambda_test.go
new file mode 100644
index 000000000..f25bf3158
--- /dev/null
+++ b/module/apmlambda/lambda_test.go
@@ -0,0 +1,36 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package apmlambda
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.elastic.co/apm/v2"
+	"go.elastic.co/fastjson"
+)
+
+func TestCreatePartialTransactionJSON(t *testing.T) {
+	var w fastjson.Writer
+	tx := apm.DefaultTracer().StartTransaction("test", "function")
+	defer tx.End()
+	assert.NoError(t, createPartialTransactionJSON(tx, &w))
+	assert.True(t, json.Valid(w.Bytes()))
+	assert.Equal(t, "test", string(w.Bytes()))
+}