diff --git a/CHANGELOG.md b/CHANGELOG.md
index 037580b..5dae597 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project follows [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Added
+
+- S3 and GCS import data sources accept an optional `import_format` (`csv`/`ndjson`/`parquet`), emitted as `IMPORT_FORMAT` in the generated `.datasource` and round-tripped by the datafile parser and migration emitter. Lets you ingest files whose extension does not imply the format (for example NDJSON delivered as `.log`), where the connector would otherwise fail with `Format not supported`.
+
 ## [0.1.11] - 2026-06-15
 
 ### Changed
diff --git a/src/tinybird_sdk/generator/datasource.py b/src/tinybird_sdk/generator/datasource.py
index fe504f1..c7693b9 100644
--- a/src/tinybird_sdk/generator/datasource.py
+++ b/src/tinybird_sdk/generator/datasource.py
@@ -121,6 +121,8 @@ def _generate_import_config(import_config: Any) -> str:
         lines.append(f"IMPORT_SCHEDULE {import_config.schedule}")
     if import_config.from_timestamp:
         lines.append(f"IMPORT_FROM_TIMESTAMP {import_config.from_timestamp}")
+    if getattr(import_config, "import_format", None):
+        lines.append(f'IMPORT_FORMAT "{import_config.import_format}"')
     return "\n".join(lines)
 
 
diff --git a/src/tinybird_sdk/migrate/emit_ts.py b/src/tinybird_sdk/migrate/emit_ts.py
index 8cde5d1..7b24142 100644
--- a/src/tinybird_sdk/migrate/emit_ts.py
+++ b/src/tinybird_sdk/migrate/emit_ts.py
@@ -249,6 +249,8 @@ def _emit_datasource(ds: DatasourceModel) -> str:
             lines.append(f"        'schedule': {_escape_string(ds.s3.schedule)},")
         if ds.s3.from_timestamp:
             lines.append(f"        'from_timestamp': {_escape_string(ds.s3.from_timestamp)},")
+        if ds.s3.import_format:
+            lines.append(f"        'import_format': {_escape_string(ds.s3.import_format)},")
         lines.append("    },")
 
     if ds.gcs:
@@ -260,6 +262,8 @@ def _emit_datasource(ds: DatasourceModel) -> str:
             lines.append(f"        'schedule': {_escape_string(ds.gcs.schedule)},")
         if ds.gcs.from_timestamp:
             lines.append(f"        'from_timestamp': {_escape_string(ds.gcs.from_timestamp)},")
+        if ds.gcs.import_format:
+            lines.append(f"        'import_format': {_escape_string(ds.gcs.import_format)},")
         lines.append("    },")
 
     if ds.dynamodb:
diff --git a/src/tinybird_sdk/migrate/parse_datasource.py b/src/tinybird_sdk/migrate/parse_datasource.py
index 53164e3..889b267 100644
--- a/src/tinybird_sdk/migrate/parse_datasource.py
+++ b/src/tinybird_sdk/migrate/parse_datasource.py
@@ -282,6 +282,7 @@ def parse_datasource_file(resource: ResourceFile) -> DatasourceModel:
     import_bucket_uri: str | None = None
     import_schedule: str | None = None
     import_from_timestamp: str | None = None
+    import_format: str | None = None
     import_table_arn: str | None = None
     import_export_bucket: str | None = None
 
@@ -416,6 +417,8 @@ def parse_datasource_file(resource: ResourceFile) -> DatasourceModel:
             import_schedule = parse_quoted_value(value)
         elif key == "IMPORT_FROM_TIMESTAMP":
             import_from_timestamp = parse_quoted_value(value)
+        elif key == "IMPORT_FORMAT":
+            import_format = parse_quoted_value(value)
         elif key == "IMPORT_TABLE_ARN":
             import_table_arn = parse_quoted_value(value)
         elif key == "IMPORT_EXPORT_BUCKET":
@@ -502,7 +505,7 @@ def parse_datasource_file(resource: ResourceFile) -> DatasourceModel:
                 resource.name,
                 "IMPORT_CONNECTION_NAME, IMPORT_TABLE_ARN and IMPORT_EXPORT_BUCKET are required for DynamoDB imports.",
             )
-        if import_bucket_uri or import_schedule or import_from_timestamp:
+        if import_bucket_uri or import_schedule or import_from_timestamp or import_format:
             raise MigrationParseError(
                 resource.file_path,
                 "datasource",
@@ -517,7 +520,11 @@ def parse_datasource_file(resource: ResourceFile) -> DatasourceModel:
 
     imported: DatasourceS3Model | None = None
     if not dynamodb and (
-        import_connection_name or import_bucket_uri or import_schedule or import_from_timestamp
+        import_connection_name
+        or import_bucket_uri
+        or import_schedule
+        or import_from_timestamp
+        or import_format
     ):
         if not import_connection_name or not import_bucket_uri:
             raise MigrationParseError(
@@ -531,6 +538,7 @@ def parse_datasource_file(resource: ResourceFile) -> DatasourceModel:
             bucket_uri=import_bucket_uri,
             schedule=import_schedule,
             from_timestamp=import_from_timestamp,
+            import_format=import_format,
         )
 
     if kafka and (imported or dynamodb):
diff --git a/src/tinybird_sdk/migrate/types.py b/src/tinybird_sdk/migrate/types.py
index 7363bdb..5b9650e 100644
--- a/src/tinybird_sdk/migrate/types.py
+++ b/src/tinybird_sdk/migrate/types.py
@@ -63,6 +63,7 @@ class DatasourceS3Model:
     bucket_uri: str
     schedule: str | None = None
     from_timestamp: str | None = None
+    import_format: str | None = None
 
 
 @dataclass(frozen=True, slots=True)
@@ -71,6 +72,7 @@ class DatasourceGCSModel:
     bucket_uri: str
     schedule: str | None = None
     from_timestamp: str | None = None
+    import_format: str | None = None
 
 
 @dataclass(frozen=True, slots=True)
diff --git a/src/tinybird_sdk/schema/datasource.py b/src/tinybird_sdk/schema/datasource.py
index c67a214..c9131b6 100644
--- a/src/tinybird_sdk/schema/datasource.py
+++ b/src/tinybird_sdk/schema/datasource.py
@@ -57,6 +57,7 @@ class S3Config:
     bucket_uri: str
     schedule: str | None = None
     from_timestamp: str | None = None
+    import_format: str | None = None
 
 
 @dataclass(frozen=True, slots=True)
@@ -65,6 +66,7 @@ class GCSConfig:
     bucket_uri: str
     schedule: str | None = None
     from_timestamp: str | None = None
+    import_format: str | None = None
 
 
 @dataclass(frozen=True, slots=True)
diff --git a/tests/test_s3_import_format.py b/tests/test_s3_import_format.py
new file mode 100644
index 0000000..0550c1c
--- /dev/null
+++ b/tests/test_s3_import_format.py
@@ -0,0 +1,113 @@
+from __future__ import annotations
+
+from tinybird_sdk import (
+    define_datasource,
+    define_gcs_connection,
+    define_s3_connection,
+    t,
+)
+from tinybird_sdk.generator.datasource import generate_datasource
+from tinybird_sdk.migrate.emit_ts import emit_migration_file_content
+from tinybird_sdk.migrate.parse_connection import parse_connection_file
+from tinybird_sdk.migrate.parse_datasource import parse_datasource_file
+from tinybird_sdk.migrate.types import ResourceFile
+
+
+def test_s3_import_emits_import_format_when_set() -> None:
+    s3 = define_s3_connection("landing_s3", {"region": "us-east-1", "arn": "arn:aws:iam::1:role/r"})
+    datasource = define_datasource(
+        "events",
+        {
+            "schema": {"id": t.string()},
+            "s3": {
+                "connection": s3,
+                "bucket_uri": "s3://bucket/events/*.log",
+                "import_format": "ndjson",
+            },
+        },
+    )
+
+    content = generate_datasource(datasource).content
+    assert "IMPORT_BUCKET_URI s3://bucket/events/*.log" in content
+    assert 'IMPORT_FORMAT "ndjson"' in content
+
+
+def test_s3_import_omits_import_format_when_unset() -> None:
+    s3 = define_s3_connection("landing_s3", {"region": "us-east-1", "arn": "arn:aws:iam::1:role/r"})
+    datasource = define_datasource(
+        "events",
+        {
+            "schema": {"id": t.string()},
+            "s3": {"connection": s3, "bucket_uri": "s3://bucket/events/*.ndjson"},
+        },
+    )
+
+    assert "IMPORT_FORMAT" not in generate_datasource(datasource).content
+
+
+def test_gcs_import_emits_import_format_when_set() -> None:
+    gcs = define_gcs_connection("landing_gcs", {"service_account_credentials_json": "{}"})
+    datasource = define_datasource(
+        "events_gcs",
+        {
+            "schema": {"id": t.string()},
+            "gcs": {
+                "connection": gcs,
+                "bucket_uri": "gs://bucket/events/*.log",
+                "import_format": "ndjson",
+            },
+        },
+    )
+
+    assert 'IMPORT_FORMAT "ndjson"' in generate_datasource(datasource).content
+
+
+def test_parse_datasource_reads_import_format() -> None:
+    resource = ResourceFile(
+        kind="datasource",
+        file_path="datasources/events.datasource",
+        absolute_path="/x/datasources/events.datasource",
+        name="events",
+        content=(
+            "SCHEMA >\n"
+            "    `id` String `json:$.id`\n"
+            "\n"
+            "IMPORT_CONNECTION_NAME 'landing_s3'\n"
+            "IMPORT_BUCKET_URI 's3://bucket/events/*.log'\n"
+            'IMPORT_FORMAT "ndjson"\n'
+        ),
+    )
+
+    model = parse_datasource_file(resource)
+    assert model.s3 is not None
+    assert model.s3.import_format == "ndjson"
+
+
+def test_emit_ts_round_trip_for_s3_import_format() -> None:
+    connection_resource = ResourceFile(
+        kind="connection",
+        file_path="connections/landing_s3.connection",
+        absolute_path="/x/connections/landing_s3.connection",
+        name="landing_s3",
+        content='TYPE s3\nS3_REGION us-east-1\nS3_ARN "arn:aws:iam::1:role/r"\n',
+    )
+    datasource_resource = ResourceFile(
+        kind="datasource",
+        file_path="datasources/events.datasource",
+        absolute_path="/x/datasources/events.datasource",
+        name="events",
+        content=(
+            "SCHEMA >\n"
+            "    `id` String `json:$.id`\n"
+            "\n"
+            "IMPORT_CONNECTION_NAME 'landing_s3'\n"
+            "IMPORT_BUCKET_URI 's3://bucket/events/*.log'\n"
+            'IMPORT_FORMAT "ndjson"\n'
+        ),
+    )
+
+    connection = parse_connection_file(connection_resource)
+    datasource = parse_datasource_file(datasource_resource)
+
+    output = emit_migration_file_content([connection, datasource])
+    assert "'import_format': \"ndjson\"" in output