diff --git a/data/deprecations/16-9-rename-kas-ca-cert-file-cli-option.yml b/data/deprecations/16-9-rename-kas-ca-cert-file-cli-option.yml
new file mode 100644
index 0000000000000000000000000000000000000000..b4c7f89315d0e6bbe0a12e3eb00b41704e497098
--- /dev/null
+++ b/data/deprecations/16-9-rename-kas-ca-cert-file-cli-option.yml
@@ -0,0 +1,18 @@
+- title: "Agent for Kubernetes option `ca-cert-file` renamed"
+  # The milestones for the deprecation announcement, and the removal.
+  removal_milestone: "17.0"
+  announcement_milestone: "16.9"
+  # Change breaking_change to false if needed.
+  breaking_change: true
+  # The stage and GitLab username of the person reporting the change,
+  # and a link to the deprecation issue
+  reporter: timofurrer
+  stage: deploy
+  issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/437728
+  body: |  # (required) Don't change this line.
+    In the GitLab agent for Kubernetes (agentk), the `--ca-cert-file` command line option
+    and the corresponding `config.caCert` Helm chart value have been renamed
+    to `--kas-ca-cert-file` and `config.kasCaCert`, respectively.
+
+    The old `--ca-cert-file` and `config.caCert` options are deprecated, and will
+    be removed in GitLab 17.0.
diff --git a/doc/update/deprecations.md b/doc/update/deprecations.md
index aaa03d847b658bb93de3ce6861a3f1924c56b99a..e6c283770299e500d39376938ff982cde4035334 100644
--- a/doc/update/deprecations.md
+++ b/doc/update/deprecations.md
@@ -227,6 +227,25 @@ From GitLab 18.0 and later, the methods to register runners introduced by the ne
 
 <div class="deprecation breaking-change" data-milestone="17.0">
 
+### Agent for Kubernetes option `ca-cert-file` renamed
+
+<div class="deprecation-notes">
+- Announced in GitLab <span class="milestone">16.9</span>
+- Removal in GitLab <span class="milestone">17.0</span> ([breaking change](https://docs.gitlab.com/ee/update/terminology.html#breaking-change))
+- To discuss this change or learn more, see the [deprecation issue](https://gitlab.com/gitlab-org/gitlab/-/issues/437728).
+</div>
+
+In the GitLab agent for Kubernetes (agentk), the `--ca-cert-file` command line option
+and the corresponding `config.caCert` Helm chart value have been renamed
+to `--kas-ca-cert-file` and `config.kasCaCert`, respectively.
+
+The old `--ca-cert-file` and `config.caCert` options are deprecated, and will
+be removed in GitLab 17.0.
+
+</div>
+
+<div class="deprecation breaking-change" data-milestone="17.0">
+
 ### Auto DevOps support for Herokuish is deprecated
 
 <div class="deprecation-notes">