diff --git a/docs/changelog/123155.yaml b/docs/changelog/123155.yaml
new file mode 100644
index 0000000000000..73027c87510ba
--- /dev/null
+++ b/docs/changelog/123155.yaml
@@ -0,0 +1,5 @@
+pr: 123155
+summary: Add `ElasticInferenceServiceCompletionServiceSettings`
+area: Machine Learning
+type: bug
+issues: []
diff --git a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferenceNamedWriteablesProvider.java b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferenceNamedWriteablesProvider.java
index e8dc763116707..2ff9fead27ec9 100644
--- a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferenceNamedWriteablesProvider.java
+++ b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferenceNamedWriteablesProvider.java
@@ -57,6 +57,7 @@
 import org.elasticsearch.xpack.inference.services.cohere.rerank.CohereRerankServiceSettings;
 import org.elasticsearch.xpack.inference.services.cohere.rerank.CohereRerankTaskSettings;
 import org.elasticsearch.xpack.inference.services.elastic.ElasticInferenceServiceSparseEmbeddingsServiceSettings;
+import org.elasticsearch.xpack.inference.services.elastic.completion.ElasticInferenceServiceCompletionServiceSettings;
 import org.elasticsearch.xpack.inference.services.elasticsearch.CustomElandInternalServiceSettings;
 import org.elasticsearch.xpack.inference.services.elasticsearch.CustomElandInternalTextEmbeddingServiceSettings;
 import org.elasticsearch.xpack.inference.services.elasticsearch.ElasticRerankerServiceSettings;
@@ -618,5 +619,12 @@ private static void addEisNamedWriteables(List<NamedWriteableRegistry.Entry> nam
                 ElasticInferenceServiceSparseEmbeddingsServiceSettings::new
             )
         );
+        namedWriteables.add(
+            new NamedWriteableRegistry.Entry(
+                ServiceSettings.class,
+                ElasticInferenceServiceCompletionServiceSettings.NAME,
+                ElasticInferenceServiceCompletionServiceSettings::new
+            )
+        );
     }
 }