diff --git a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapper.java b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapper.java
index 08d11f7bd41f2..ca1d8f75542b4 100644
--- a/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapper.java
+++ b/x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapper.java
@@ -129,8 +129,7 @@ protected void merge(FieldMapper mergeWith, Conflicts conflicts, MapperMergeCont
             var semanticMergeWith = (SemanticTextFieldMapper) mergeWith;
             var context = mapperMergeContext.createChildContext(mergeWith.simpleName(), ObjectMapper.Dynamic.FALSE);
             var inferenceField = inferenceFieldBuilder.apply(context.getMapperBuilderContext());
-            var childContext = context.createChildContext(inferenceField.simpleName(), ObjectMapper.Dynamic.FALSE);
-            var mergedInferenceField = inferenceField.merge(semanticMergeWith.fieldType().getInferenceField(), childContext);
+            var mergedInferenceField = inferenceField.merge(semanticMergeWith.fieldType().getInferenceField(), context);
             inferenceFieldBuilder = c -> mergedInferenceField;
         }
 
diff --git a/x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapperTests.java b/x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapperTests.java
index a6f0fa83eab37..9392a3184e3ac 100644
--- a/x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapperTests.java
+++ b/x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/mapper/SemanticTextFieldMapperTests.java
@@ -19,12 +19,16 @@
 import org.apache.lucene.search.join.BitSetProducer;
 import org.apache.lucene.search.join.QueryBitSetProducer;
 import org.apache.lucene.search.join.ScoreMode;
+import org.elasticsearch.action.admin.indices.mapping.put.PutMappingRequest;
 import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.bytes.BytesArray;
+import org.elasticsearch.common.compress.CompressedXContent;
 import org.elasticsearch.common.lucene.search.Queries;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.index.IndexVersion;
 import org.elasticsearch.index.mapper.DocumentMapper;
 import org.elasticsearch.index.mapper.DocumentParsingException;
+import org.elasticsearch.index.mapper.FieldMapper;
 import org.elasticsearch.index.mapper.KeywordFieldMapper;
 import org.elasticsearch.index.mapper.LuceneDocument;
 import org.elasticsearch.index.mapper.MappedFieldType;
@@ -35,6 +39,7 @@
 import org.elasticsearch.index.mapper.NestedLookup;
 import org.elasticsearch.index.mapper.NestedObjectMapper;
 import org.elasticsearch.index.mapper.ParsedDocument;
+import org.elasticsearch.index.mapper.SourceToParse;
 import org.elasticsearch.index.mapper.vectors.DenseVectorFieldMapper;
 import org.elasticsearch.index.mapper.vectors.SparseVectorFieldMapper;
 import org.elasticsearch.index.search.ESToParentBlockJoinQuery;
@@ -168,6 +173,45 @@ public void testUpdatesToInferenceIdNotSupported() throws IOException {
         assertThat(e.getMessage(), containsString("Cannot update parameter [inference_id] from [test_model] to [another_model]"));
     }
 
+    public void testDynamicUpdate() throws IOException {
+        MapperService mapperService = createMapperService(mapping(b -> {}));
+        mapperService.merge(
+            "_doc",
+            new CompressedXContent(
+                Strings.toString(PutMappingRequest.simpleMapping("semantic", "type=semantic_text,inference_id=test_service"))
+            ),
+            MapperService.MergeReason.MAPPING_UPDATE
+        );
+        String source = """
+            {
+              "semantic": {
+                "inference": {
+                  "inference_id": "test_service",
+                  "model_settings": {
+                    "task_type": "SPARSE_EMBEDDING"
+                  },
+                  "chunks": [
+                    {
+                      "embeddings": {
+                        "feature_0": 1
+                      },
+                      "text": "feature_0"
+                    }
+                  ]
+                }
+              }
+            }
+            """;
+        SourceToParse sourceToParse = new SourceToParse("test", new BytesArray(source), XContentType.JSON);
+        ParsedDocument parsedDocument = mapperService.documentMapper().parse(sourceToParse);
+        mapperService.merge(
+            "_doc",
+            parsedDocument.dynamicMappingsUpdate().toCompressedXContent(),
+            MapperService.MergeReason.MAPPING_UPDATE
+        );
+        assertSemanticTextField(mapperService, "semantic", true);
+    }
+
     public void testUpdateModelSettings() throws IOException {
         for (int depth = 1; depth < 5; depth++) {
             String fieldName = randomFieldName(depth);
@@ -270,6 +314,7 @@ static void assertSemanticTextField(MapperService mapperService, String fieldNam
             .getNestedMappers()
             .get(getChunksFieldName(fieldName));
         assertThat(chunksMapper, equalTo(semanticFieldMapper.fieldType().getChunksField()));
+        assertThat(chunksMapper.name(), equalTo(getChunksFieldName(fieldName)));
         Mapper textMapper = chunksMapper.getMapper(CHUNKED_TEXT_FIELD.getPreferredName());
         assertNotNull(textMapper);
         assertThat(textMapper, instanceOf(KeywordFieldMapper.class));
@@ -278,11 +323,15 @@ static void assertSemanticTextField(MapperService mapperService, String fieldNam
         assertFalse(textFieldMapper.fieldType().hasDocValues());
         if (expectedModelSettings) {
             assertNotNull(semanticFieldMapper.fieldType().getModelSettings());
-            Mapper inferenceMapper = chunksMapper.getMapper(CHUNKED_EMBEDDINGS_FIELD.getPreferredName());
-            assertNotNull(inferenceMapper);
+            Mapper embeddingsMapper = chunksMapper.getMapper(CHUNKED_EMBEDDINGS_FIELD.getPreferredName());
+            assertNotNull(embeddingsMapper);
+            assertThat(embeddingsMapper, instanceOf(FieldMapper.class));
+            FieldMapper embeddingsFieldMapper = (FieldMapper) embeddingsMapper;
+            assertTrue(embeddingsFieldMapper.fieldType() == mapperService.mappingLookup().getFieldType(getEmbeddingsFieldName(fieldName)));
+            assertThat(embeddingsMapper.name(), equalTo(getEmbeddingsFieldName(fieldName)));
             switch (semanticFieldMapper.fieldType().getModelSettings().taskType()) {
-                case SPARSE_EMBEDDING -> assertThat(inferenceMapper, instanceOf(SparseVectorFieldMapper.class));
-                case TEXT_EMBEDDING -> assertThat(inferenceMapper, instanceOf(DenseVectorFieldMapper.class));
+                case SPARSE_EMBEDDING -> assertThat(embeddingsMapper, instanceOf(SparseVectorFieldMapper.class));
+                case TEXT_EMBEDDING -> assertThat(embeddingsMapper, instanceOf(DenseVectorFieldMapper.class));
                 default -> throw new AssertionError("Invalid task type");
             }
         } else {