diff --git a/README.md b/README.md
index 6da3ee1d9..4d883a4cd 100644
--- a/README.md
+++ b/README.md
@@ -186,6 +186,16 @@ result = md.convert("test.xlsx")
 print(result.text_content)
 ```
 
+To preserve underlined text from supported sources such as DOCX as literal HTML underline tags:
+
+```python
+from markitdown import MarkItDown
+
+md = MarkItDown(preserve_underlines=True)
+result = md.convert("underlined.docx")
+print(result.text_content)  # e.g. "<u>important</u>"
+```
+
 Document Intelligence conversion in Python:
 
 ```python
diff --git a/packages/markitdown/src/markitdown/_markitdown.py b/packages/markitdown/src/markitdown/_markitdown.py
index f342a614b..86278a018 100644
--- a/packages/markitdown/src/markitdown/_markitdown.py
+++ b/packages/markitdown/src/markitdown/_markitdown.py
@@ -125,6 +125,7 @@ def __init__(
         self._llm_prompt: Union[str | None] = None
         self._exiftool_path: Union[str | None] = None
         self._style_map: Union[str | None] = None
+        self._preserve_underlines: bool = False
 
         # Register the converters
         self._converters: List[ConverterRegistration] = []
@@ -150,6 +151,7 @@ def enable_builtins(self, **kwargs) -> None:
             self._llm_prompt = kwargs.get("llm_prompt")
             self._exiftool_path = kwargs.get("exiftool_path")
             self._style_map = kwargs.get("style_map")
+            self._preserve_underlines = kwargs.get("preserve_underlines", False)
 
             if self._exiftool_path is None:
                 self._exiftool_path = os.getenv("EXIFTOOL_PATH")
@@ -577,6 +579,12 @@ def _convert(
                 if "exiftool_path" not in _kwargs and self._exiftool_path is not None:
                     _kwargs["exiftool_path"] = self._exiftool_path
 
+                if (
+                    "preserve_underlines" not in _kwargs
+                    and self._preserve_underlines
+                ):
+                    _kwargs["preserve_underlines"] = self._preserve_underlines
+
                 # Add the list of converters for nested processing
                 _kwargs["_parent_converters"] = self._converters
 
diff --git a/packages/markitdown/src/markitdown/converters/_docx_converter.py b/packages/markitdown/src/markitdown/converters/_docx_converter.py
index 3975107b1..e399c6085 100644
--- a/packages/markitdown/src/markitdown/converters/_docx_converter.py
+++ b/packages/markitdown/src/markitdown/converters/_docx_converter.py
@@ -26,6 +26,20 @@
 ]
 
 ACCEPTED_FILE_EXTENSIONS = [".docx"]
+UNDERLINE_STYLE_MAP = "u => u"
+
+
+def _merge_underline_style_map(style_map: str | None) -> str:
+    """Add the Mammoth underline mapping unless the caller already supplied one."""
+
+    if style_map is None or not style_map.strip():
+        return UNDERLINE_STYLE_MAP
+
+    for line in style_map.splitlines():
+        if line.strip().startswith("u =>"):
+            return style_map
+
+    return f"{style_map.rstrip()}\n{UNDERLINE_STYLE_MAP}"
 
 
 class DocxConverter(HtmlConverter):
@@ -76,6 +90,8 @@ def convert(
             )
 
         style_map = kwargs.get("style_map", None)
+        if kwargs.get("preserve_underlines"):
+            style_map = _merge_underline_style_map(style_map)
         pre_process_stream = pre_process_docx(file_stream)
         return self._html_converter.convert_string(
             mammoth.convert_to_html(pre_process_stream, style_map=style_map).value,
diff --git a/packages/markitdown/src/markitdown/converters/_markdownify.py b/packages/markitdown/src/markitdown/converters/_markdownify.py
index 19e8a2984..d8c5931ec 100644
--- a/packages/markitdown/src/markitdown/converters/_markdownify.py
+++ b/packages/markitdown/src/markitdown/converters/_markdownify.py
@@ -18,6 +18,7 @@ class _CustomMarkdownify(markdownify.MarkdownConverter):
     def __init__(self, **options: Any):
         options["heading_style"] = options.get("heading_style", markdownify.ATX)
         options["keep_data_uris"] = options.get("keep_data_uris", False)
+        options["preserve_underlines"] = options.get("preserve_underlines", False)
         # Explicitly cast options to the expected type if necessary
         super().__init__(**options)
 
@@ -122,5 +123,23 @@ def convert_input(
             return "[x] " if el.has_attr("checked") else "[ ] "
         return ""
 
+    def convert_u(
+        self,
+        el: Any,
+        text: str,
+        convert_as_inline: Optional[bool] = False,
+        **kwargs,
+    ) -> str:
+        """Optionally preserve underline markup as literal HTML tags."""
+
+        if not self.options["preserve_underlines"]:
+            return text
+
+        prefix, suffix, text = markdownify.chomp(text)  # type: ignore
+        if not text:
+            return ""
+
+        return f"{prefix}<u>{text}</u>{suffix}"
+
     def convert_soup(self, soup: Any) -> str:
         return super().convert_soup(soup)  # type: ignore
diff --git a/packages/markitdown/tests/test_module_misc.py b/packages/markitdown/tests/test_module_misc.py
index 8e3acc23d..21b878a37 100644
--- a/packages/markitdown/tests/test_module_misc.py
+++ b/packages/markitdown/tests/test_module_misc.py
@@ -5,8 +5,11 @@
 import shutil
 import pytest
 from unittest.mock import MagicMock
+from unittest.mock import patch
 
 from markitdown._uri_utils import parse_data_uri, file_uri_to_path
+from markitdown._base_converter import DocumentConverterResult
+from markitdown.converters._docx_converter import DocxConverter
 
 from markitdown import (
     MarkItDown,
@@ -274,6 +277,81 @@ def test_docx_equations() -> None:
     assert block_equations, "No block equations found in the document."
 
 
+def test_html_preserve_underlines() -> None:
+    html = b"<html><body><p>alpha <u>beta</u> gamma</p></body></html>"
+
+    default_result = MarkItDown().convert_stream(
+        io.BytesIO(html),
+        stream_info=StreamInfo(extension=".html"),
+    )
+    assert "<u>beta</u>" not in default_result.text_content
+    assert "alpha beta gamma" in default_result.text_content
+
+    preserved_result = MarkItDown(preserve_underlines=True).convert_stream(
+        io.BytesIO(html),
+        stream_info=StreamInfo(extension=".html"),
+    )
+    assert "alpha <u>beta</u> gamma" in preserved_result.text_content
+
+
+def test_docx_preserve_underlines_adds_style_map() -> None:
+    converter = DocxConverter()
+    converter._html_converter.convert_string = MagicMock(
+        return_value=DocumentConverterResult(markdown="<u>underlined</u>")
+    )
+
+    with (
+        patch(
+            "markitdown.converters._docx_converter.pre_process_docx",
+            return_value=io.BytesIO(b"fake"),
+        ),
+        patch(
+            "markitdown.converters._docx_converter.mammoth.convert_to_html",
+            return_value=MagicMock(value="<p><u>underlined</u></p>"),
+        ) as convert_to_html,
+    ):
+        converter.convert(
+            io.BytesIO(b"fake"),
+            StreamInfo(extension=".docx"),
+            preserve_underlines=True,
+        )
+
+    assert convert_to_html.call_args.kwargs["style_map"] == "u => u"
+    converter._html_converter.convert_string.assert_called_once_with(
+        "<p><u>underlined</u></p>",
+        preserve_underlines=True,
+    )
+
+
+def test_docx_preserve_underlines_merges_existing_style_map() -> None:
+    converter = DocxConverter()
+    converter._html_converter.convert_string = MagicMock(
+        return_value=DocumentConverterResult(markdown="<u>underlined</u>")
+    )
+
+    with (
+        patch(
+            "markitdown.converters._docx_converter.pre_process_docx",
+            return_value=io.BytesIO(b"fake"),
+        ),
+        patch(
+            "markitdown.converters._docx_converter.mammoth.convert_to_html",
+            return_value=MagicMock(value="<p><u>underlined</u></p>"),
+        ) as convert_to_html,
+    ):
+        converter.convert(
+            io.BytesIO(b"fake"),
+            StreamInfo(extension=".docx"),
+            preserve_underlines=True,
+            style_map="comment-reference => ",
+        )
+
+    assert (
+        convert_to_html.call_args.kwargs["style_map"]
+        == "comment-reference =>\nu => u"
+    )
+
+
 def test_input_as_strings() -> None:
     markitdown = MarkItDown()