diff --git a/changelog/fragments/1751029489-synth-upgra-node-v20.yaml b/changelog/fragments/1751029489-synth-upgra-node-v20.yaml
new file mode 100644
index 00000000000..0e2a83d1728
--- /dev/null
+++ b/changelog/fragments/1751029489-synth-upgra-node-v20.yaml
@@ -0,0 +1,32 @@
+# Kind can be one of:
+# - breaking-change: a change to previously-documented behavior
+# - deprecation: functionality that is being removed in a later release
+# - bug-fix: fixes a problem in a previous version
+# - enhancement: extends functionality but does not break or fix existing behavior
+# - feature: new functionality
+# - known-issue: problems that we are aware of in a given version
+# - security: impacts on the security of a product or a user’s deployment.
+# - upgrade: important information for someone upgrading from a prior version
+# - other: does not fit into any of the other categories
+kind: other
+
+# Change summary; a 80ish characters long description of the change.
+summary: Upgrade Synthetics NodeJS version to latest LTS v20.
+
+# Long description; in case the summary is not enough to describe the change
+# this field accommodate a description without length limits.
+# NOTE: This field will be rendered only for breaking-change and known-issue kinds at the moment.
+# description:
+
+# Affected component; usually one of "elastic-agent", "fleet-server", "filebeat", "metricbeat", "auditbeat", "all", etc.
+component: heartbeat
+
+# PR URL; optional; the PR number that added the changeset.
+# If not present is automatically filled by the tooling finding the PR where this changelog fragment has been added.
+# NOTE: the tooling supports backports, so it's able to fill the original PR number instead of the backport PR number.
+# Please provide it if you are adding a fragment for a different PR.
+pr: https://github.com/elastic/elastic-agent/pull/8712
+
+# Issue URL; optional; the GitHub issue related to this changeset (either closes or is part of).
+# If not present is automatically filled by the tooling with the issue linked to the PR number.
+#issue: https://github.com/owner/repo/1234
diff --git a/dev-tools/packaging/templates/docker/Dockerfile.elastic-agent.tmpl b/dev-tools/packaging/templates/docker/Dockerfile.elastic-agent.tmpl
index 014cb7397d3..67c2ada11f2 100644
--- a/dev-tools/packaging/templates/docker/Dockerfile.elastic-agent.tmpl
+++ b/dev-tools/packaging/templates/docker/Dockerfile.elastic-agent.tmpl
@@ -206,7 +206,7 @@ RUN echo \
 ENV ELASTIC_SYNTHETICS_CAPABLE=true
 ENV ELASTIC_AGENT_COMPLETE=true
 ENV TZ=UTC
-ENV NODE_VERSION=18.20.7
+ENV NODE_VERSION=20.19.3
 ENV PATH="$NODE_PATH/node/bin:$PATH"
 # Install the latest version of @elastic/synthetics forcefully ignoring the previously
 # cached node_modules, heartbeat then calls the global executable to run test suites
@@ -269,7 +269,7 @@ USER root
 # Install required dependencies from wolfi repository
 RUN for iter in {1..10}; do \
         apk fix && \
-        apk add --no-interactive --no-progress --no-cache nodejs-18=18.20.7-r0 npm=10.9.2-r0 glib dbus-glib libatk-1.0 \
+        apk add --no-interactive --no-progress --no-cache nodejs-20=20.19.3-r0 npm=11.4.2-r0 glib dbus-glib libatk-1.0 \
         libatk-bridge-2.0 cups-libs libxcomposite libxdamage libxrandr libxkbcommon pango alsa-lib \
         font-opensans fontconfig gtk icu-data-full libnss mesa font-noto-cjk font-noto-emoji && \
         exit_code=0 && break || exit_code=$? && echo "apk error: retry $iter in 10s" && sleep 10; \