diff --git a/superset/charts/data/api.py b/superset/charts/data/api.py
index d6ddd595981..3cbeccde271 100644
--- a/superset/charts/data/api.py
+++ b/superset/charts/data/api.py
@@ -524,8 +524,11 @@ class ChartDataRestApi(ChartRestApi):
             # return multi-query results bundled as a zip file
             def _process_data(query_data: Any) -> Any:
                 if result_format == ChartDataResultFormat.CSV:
-                    encoding = app.config["CSV_EXPORT"].get("encoding", "utf-8")
-                    return query_data.encode(encoding)
+                    # CSV data is already encoded to bytes by the query context
+                    # processor, honoring the CSV_EXPORT encoding config.
+                    if isinstance(query_data, str):
+                        encoding = app.config["CSV_EXPORT"].get("encoding", "utf-8")
+                        return query_data.encode(encoding)
                 return query_data
 
             files = {
diff --git a/superset/common/query_context.py b/superset/common/query_context.py
index ed39aff078f..bef870035c0 100644
--- a/superset/common/query_context.py
+++ b/superset/common/query_context.py
@@ -87,7 +87,7 @@ class QueryContext:
         self,
         df: pd.DataFrame,
         coltypes: list[GenericDataType],
-    ) -> str | list[dict[str, Any]]:
+    ) -> str | bytes | list[dict[str, Any]]:
         return self._processor.get_data(df, coltypes)
 
     def get_payload(
diff --git a/superset/common/query_context_processor.py b/superset/common/query_context_processor.py
index bee3d6eb0df..bd7e8c9ccbe 100644
--- a/superset/common/query_context_processor.py
+++ b/superset/common/query_context_processor.py
@@ -257,7 +257,7 @@ class QueryContextProcessor:
 
     def get_data(
         self, df: pd.DataFrame, coltypes: list[GenericDataType]
-    ) -> str | list[dict[str, Any]]:
+    ) -> str | bytes | list[dict[str, Any]]:
         if self._query_context.result_format in ChartDataResultFormat.table_like():
             include_index = not isinstance(df.index, pd.RangeIndex)
             columns = list(df.columns)
@@ -270,6 +270,11 @@ class QueryContextProcessor:
                 result = csv.df_to_escaped_csv(
                     df, index=include_index, **current_app.config["CSV_EXPORT"]
                 )
+                # Encode using the configured CSV_EXPORT encoding (default utf-8)
+                # so dashboard chart exports honor the same encoding as SQL Lab.
+                result = result.encode(
+                    current_app.config["CSV_EXPORT"].get("encoding", "utf-8")
+                )
             elif self._query_context.result_format == ChartDataResultFormat.XLSX:
                 excel.apply_column_types(df, coltypes)
                 result = excel.df_to_excel(
diff --git a/tests/unit_tests/common/test_query_context_processor.py b/tests/unit_tests/common/test_query_context_processor.py
index 6e4acc08b41..0272658c2d6 100644
--- a/tests/unit_tests/common/test_query_context_processor.py
+++ b/tests/unit_tests/common/test_query_context_processor.py
@@ -107,7 +107,9 @@ def test_get_data_csv(mock_df_to_escaped_csv, processor, mock_query_context):
 
     mock_df_to_escaped_csv.return_value = "col1,col2\n1,a\n2,b\n3,c\n"
     result = processor.get_data(df, coltypes)
-    assert result == "col1,col2\n1,a\n2,b\n3,c\n"
+    # CSV output is encoded to bytes using the CSV_EXPORT encoding so dashboard
+    # chart exports honor the configured encoding (e.g. the utf-8-sig BOM).
+    assert result == "col1,col2\n1,a\n2,b\n3,c\n".encode("utf-8-sig")
     mock_df_to_escaped_csv.assert_called_once_with(
         df, index=False, encoding="utf-8-sig"
     )
@@ -183,7 +185,7 @@ def test_get_data_empty_dataframe_csv(
     mock_query_context.result_format = ChartDataResultFormat.CSV
     mock_df_to_escaped_csv.return_value = "col1,col2\n"
     result = processor.get_data(df, coltypes)
-    assert result == "col1,col2\n"
+    assert result == "col1,col2\n".encode("utf-8-sig")
     mock_df_to_escaped_csv.assert_called_once_with(
         df, index=False, encoding="utf-8-sig"
     )