diff --git a/src/towncrier/_builder.py b/src/towncrier/_builder.py
index dca09da6..8c9bbeb6 100644
--- a/src/towncrier/_builder.py
+++ b/src/towncrier/_builder.py
@@ -7,11 +7,21 @@
 import os
 import re
 import textwrap
+import unicodedata
 
 from collections import defaultdict
 from fnmatch import fnmatch
 from pathlib import Path
-from typing import Any, DefaultDict, Iterable, Iterator, Mapping, NamedTuple, Sequence
+from typing import (
+    Any,
+    DefaultDict,
+    Iterable,
+    Iterator,
+    Mapping,
+    NamedTuple,
+    Sequence,
+    TypeAlias,
+)
 
 from click import ClickException
 from jinja2 import Template
@@ -19,6 +29,9 @@
 from towncrier._settings.load import Config
 
 
+UnderlineLengthType: TypeAlias = float | str | int | dict[Any, Any] | list[Any]
+
+
 # Returns issue, category and counter or (None, None, None) if the basename
 # could not be parsed or doesn't contain a valid category.
 def parse_newfragment_basename(
@@ -203,6 +216,49 @@ def find_fragments(
     return content, fragment_files
 
 
+def get_dict_length(obj: dict[UnderlineLengthType, UnderlineLengthType]) -> int:
+    """
+    Gets the sum of the underline lengths for all keys and values in a dictionary.
+    """
+    return sum(
+        get_underline_length(key) + get_underline_length(value)
+        for key, value in obj.items()
+    )
+
+
+def get_list_length(obj: list[UnderlineLengthType]) -> int:
+    """
+    Gets the sum of the underline lengths for all items in a list.
+    """
+    return sum(get_underline_length(item) for item in obj)
+
+
+def get_string_length(text: str) -> int:
+    """
+    Determines the amount of characters needed to underline a string.
+    """
+    return sum(
+        2 if unicodedata.east_asian_width(char) in ("W", "F") else 1 for char in text
+    )
+
+
+def get_underline_length(obj: UnderlineLengthType) -> int:
+    """
+    Given `obj` determine the underline length needed for the reStructuredText output.
+
+    Particularly helps determine if an extra underline is needed for wide characters like emojis.
+    """
+    if isinstance(obj, dict):
+        return get_dict_length(obj)
+    elif isinstance(obj, list):
+        return get_list_length(obj)
+    elif isinstance(obj, str):
+        return get_string_length(obj)
+    elif isinstance(obj, int) or isinstance(obj, float):
+        return len(str(obj))
+    raise TypeError("Object must be a string, int, float, list, or dictionary.")
+
+
 def indent(text: str, prefix: str) -> str:
     """
     Adds `prefix` to the beginning of non-empty lines in `text`.
@@ -411,6 +467,7 @@ def get_indent(text: str) -> str:
         top_underline=top_underline,
         get_indent=get_indent,  # simplify indentation in the jinja template.
         issues_by_category=issues_by_category,
+        get_underline_length=get_underline_length,  # helps determine length for non-ascii chars
     )
 
     for line in res.split("\n"):
diff --git a/src/towncrier/build.py b/src/towncrier/build.py
index 3d183925..d6eed7fd 100644
--- a/src/towncrier/build.py
+++ b/src/towncrier/build.py
@@ -19,7 +19,12 @@
 
 from towncrier import _git
 
-from ._builder import find_fragments, render_fragments, split_fragments
+from ._builder import (
+    find_fragments,
+    get_underline_length,
+    render_fragments,
+    split_fragments,
+)
 from ._project import get_project_name, get_version
 from ._settings import ConfigError, config_option_help, load_config_from_options
 from ._writer import append_to_newsfile
@@ -234,7 +239,7 @@ def __main(
         if is_markdown:
             parts = [top_line]
         else:
-            parts = [top_line, config.underlines[0] * len(top_line)]
+            parts = [top_line, config.underlines[0] * get_underline_length(top_line)]
         parts.append(rendered)
         content = "\n".join(parts)
     else:
diff --git a/src/towncrier/newsfragments/626.bugfix.rst b/src/towncrier/newsfragments/626.bugfix.rst
new file mode 100644
index 00000000..080af58e
--- /dev/null
+++ b/src/towncrier/newsfragments/626.bugfix.rst
@@ -0,0 +1,2 @@
+For reStructuredText format, you can now use emojis in category names.
+In previous versions, the generated underline was not matching the title width.
diff --git a/src/towncrier/templates/default.rst b/src/towncrier/templates/default.rst
index bee15720..9b196e79 100644
--- a/src/towncrier/templates/default.rst
+++ b/src/towncrier/templates/default.rst
@@ -1,29 +1,29 @@
 {% if render_title %}
 {% if versiondata.name %}
 {{ versiondata.name }} {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.name + versiondata.version + versiondata.date)|length + 4)}}
+{{ top_underline * (get_underline_length(versiondata.name + versiondata.version + versiondata.date) + 4)}}
 {% else %}
 {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.version + versiondata.date)|length + 3)}}
+{{ top_underline * (get_underline_length(versiondata.version + versiondata.date) + 3)}}
 {% endif %}
 {% endif %}
 {% for section, _ in sections.items() %}
 {% set underline = underlines[0] %}{% if section %}{{section}}
-{{ underline * section|length }}{% set underline = underlines[1] %}
+{{ underline * get_underline_length(section) }}{% set underline = underlines[1] %}
 
 {% endif %}
 
 {% if sections[section] %}
 {% for category, val in definitions.items() if category in sections[section]%}
 {{ definitions[category]['name'] }}
-{{ underline * definitions[category]['name']|length }}
+{{ underline * get_underline_length(definitions[category]['name']) }}
 
 {% for text, values in sections[section][category].items() %}
 - {% if text %}{{ text }}{% if values %} ({{ values|join(', ') }}){% endif %}{% else %}{{ values|join(', ') }}{% endif  %}
 
 {% endfor %}
 
-{% if sections[section][category]|length == 0 %}
+{% if get_underline_length(sections[section][category]) == 0 %}
 No significant changes.
 
 {% else %}
diff --git a/src/towncrier/templates/hr-between-versions.rst b/src/towncrier/templates/hr-between-versions.rst
index 455e571d..675196e0 100644
--- a/src/towncrier/templates/hr-between-versions.rst
+++ b/src/towncrier/templates/hr-between-versions.rst
@@ -1,22 +1,22 @@
 {% if render_title %}
 {% if versiondata.name %}
 {{ versiondata.name }} {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.name + versiondata.version + versiondata.date)|length + 4)}}
+{{ top_underline * (get_underline_length(versiondata.name + versiondata.version + versiondata.date) + 4)}}
 {% else %}
 {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.version + versiondata.date)|length + 3)}}
+{{ top_underline * (get_underline_length(versiondata.version + versiondata.date) + 3)}}
 {% endif %}
 {% endif %}
 {% for section, _ in sections.items() %}
 {% set underline = underlines[0] %}{% if section %}{{section}}
-{{ underline * section|length }}{% set underline = underlines[1] %}
+{{ underline * get_underline_length(section) }}{% set underline = underlines[1] %}
 
 {% endif %}
 
 {% if sections[section] %}
 {% for category, val in definitions.items() if category in sections[section]%}
 {{ definitions[category]['name'] }}
-{{ underline * definitions[category]['name']|length }}
+{{ underline * get_underline_length(definitions[category]['name']) }}
 
 {% if definitions[category]['showcontent'] %}
 {% for text, values in sections[section][category].items() %}
@@ -28,7 +28,7 @@
 - {{ sections[section][category]['']|join(', ') }}
 
 {% endif %}
-{% if sections[section][category]|length == 0 %}
+{% if get_underline_length(sections[section][category]) == 0 %}
 No significant changes.
 
 {% else %}
diff --git a/src/towncrier/templates/single-file-no-bullets.rst b/src/towncrier/templates/single-file-no-bullets.rst
index 5b83c515..7fbc34d0 100644
--- a/src/towncrier/templates/single-file-no-bullets.rst
+++ b/src/towncrier/templates/single-file-no-bullets.rst
@@ -1,22 +1,22 @@
 {% if render_title %}
 {% if versiondata.name %}
 {{ versiondata.name }} {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.name + versiondata.version + versiondata.date)|length + 4)}}
+{{ top_underline * (get_underline_length(versiondata.name + versiondata.version + versiondata.date) + 4)}}
 {% else %}
 {{ versiondata.version }} ({{ versiondata.date }})
-{{ top_underline * ((versiondata.version + versiondata.date)|length + 3)}}
+{{ top_underline * (get_underline_length(versiondata.version + versiondata.date) + 3)}}
 {% endif %}
 {% endif %}
 {% for section, _ in sections.items() %}
 {% set underline = underlines[0] %}{% if section %}{{section}}
-{{ underline * section|length }}{% set underline = underlines[1] %}
+{{ underline * get_underline_length(section) }}{% set underline = underlines[1] %}
 
 {% endif %}
 {% if sections[section] %}
 {% for category, val in definitions.items() if category in sections[section] %}
 
 {{ definitions[category]['name'] }}
-{{ underline * definitions[category]['name']|length }}
+{{ underline * get_underline_length(definitions[category]['name']) }}
 
 {% if definitions[category]['showcontent'] %}
 {% for text, values in sections[section][category].items() %}
@@ -28,7 +28,7 @@
 - {{ sections[section][category]['']|join(', ') }}
 
 {% endif %}
-{% if sections[section][category]|length == 0 %}
+{% if get_underline_length(sections[section][category]) == 0 %}
 No significant changes.
 
 {% else %}
diff --git a/src/towncrier/test/helpers.py b/src/towncrier/test/helpers.py
index 77cea36d..b3727a1f 100644
--- a/src/towncrier/test/helpers.py
+++ b/src/towncrier/test/helpers.py
@@ -29,7 +29,7 @@ def write(path: str | Path, contents: str, dedent: bool = False) -> None:
     p.parent.mkdir(parents=True, exist_ok=True)
     if dedent:
         contents = textwrap.dedent(contents)
-    p.write_text(contents)
+    p.write_text(contents, encoding="utf-8")
 
 
 def read_pkg_resource(path: str) -> str:
@@ -65,9 +65,9 @@ def setup_simple_project(
         config = "[tool.towncrier]\n" 'package = "foo"\n' + extra_config
     else:
         config = textwrap.dedent(config)
-    Path(pyproject_path).write_text(config)
+    Path(pyproject_path).write_text(config, encoding="utf-8")
     Path("foo").mkdir()
-    Path("foo/__init__.py").write_text('__version__ = "1.2.3"\n')
+    Path("foo/__init__.py").write_text('__version__ = "1.2.3"\n', encoding="utf-8")
 
     if mkdir_newsfragments:
         Path("foo/newsfragments").mkdir()
diff --git a/src/towncrier/test/test_build.py b/src/towncrier/test/test_build.py
index 0092d495..35df3fad 100644
--- a/src/towncrier/test/test_build.py
+++ b/src/towncrier/test/test_build.py
@@ -1398,6 +1398,62 @@ def test_default_start_string_markdown(self, runner):
 
         self.assertEqual(expected_output, output)
 
+    @with_project(
+        config="""
+        [tool.towncrier]
+        name = "🍫 FooBar"
+
+          [[tool.towncrier.type]]
+          directory = "bugfix"
+          name = "🐛 Bugfixes"
+          showcontent = true
+        """
+    )
+    def test_underline_length_unicode(self, runner):
+        """
+        The news file can be generated for project names,
+        and categories that contains emoji in their names.
+
+        This is a test for generating the RST section
+        underline to meet the docutils requirements.
+        """
+        os.mkdir("newsfragments")
+        with open("newsfragments/321.bugfix", "w") as f:
+            f.write("Squashed a bug")
+
+        result = runner.invoke(
+            _main,
+            [
+                "--version=7.8.9",
+                "--date=01-01-2001",
+                "--draft",
+            ],
+        )
+
+        expected_output = dedent(
+            """\
+            Loading template...
+            Finding news fragments...
+            Rendering news fragments...
+            Draft only -- nothing has been written.
+            What is seen below is what would be written.
+
+            🍫 FooBar 7.8.9 (01-01-2001)
+            ============================
+
+            🐛 Bugfixes
+            -----------
+
+            - Squashed a bug (#321)
+
+
+
+        """
+        )
+
+        self.assertEqual(0, result.exit_code, result.output)
+        self.assertEqual(expected_output, result.output)
+
     @with_project(
         config="""
         [tool.towncrier]
diff --git a/src/towncrier/test/test_builder.py b/src/towncrier/test/test_builder.py
index 31108fdf..63bac4fd 100644
--- a/src/towncrier/test/test_builder.py
+++ b/src/towncrier/test/test_builder.py
@@ -5,7 +5,11 @@
 
 from twisted.trial.unittest import TestCase
 
-from .._builder import parse_newfragment_basename, render_fragments
+from .._builder import (
+    get_underline_length,
+    parse_newfragment_basename,
+    render_fragments,
+)
 
 
 class TestParseNewsfragmentBasename(TestCase):
@@ -41,6 +45,34 @@ def test_counter_with_extension(self):
             ("123", "feature", 1),
         )
 
+    def test_get_underline_length_ascii(self):
+        """Determine underline size for normal ASCII strings."""
+        assert get_underline_length("bugfixes") == 8
+
+    def test_get_underline_length_wide_character(self):
+        """Determine underline size for strings with wide characters."""
+        assert get_underline_length("🐛 Bugfixes") == 11
+
+    def test_get_underline_length_list_of_lists(self):
+        """Determine underline size for lists."""
+        assert get_underline_length([["a", "b"], ["c", "d"]]) == 4
+
+    def test_get_underline_length_dict_of_dicts(self):
+        """Determine underline size for dictionaries."""
+        assert get_underline_length({"a": {"b": "c"}, "d": {"e": "f"}}) == 6
+
+    def test_get_underline_length_int(self):
+        """Determine underline size for integers."""
+        assert get_underline_length(123) == 3
+
+    def test_get_underline_length_float(self):
+        """Determine underline size for floats."""
+        assert get_underline_length(123.5) == 5
+
+    def test_get_underline_length_wrong_type(self):
+        """Determine underline size for wrong type."""
+        self.assertRaises(TypeError, get_underline_length, None)
+
     def test_ignores_extension(self):
         """File extensions are ignored."""
         self.assertEqual(