diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f99f3c..9e9031a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- `--enable-line-numbers` CLI flag to opt in to line numbers for Confluence code blocks
+
 ### Fixed
 
 - Pass title prefix through rendering pipeline so Confluence anchors use the correct prefixed page title
@@ -15,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- **BREAKING (pre-1.0):** Confluence code block line numbers are now **off by default**. Existing users will lose line numbers on their next upload unless they pass `--enable-line-numbers`.
 - Use stdlib `html.parser.HTMLParser` for robust HTML-to-XHTML conversion instead of regex
 - Use dynamic default branch detection in publish-release script
 
diff --git a/README.md b/README.md
index 693fe7f..4fe7090 100644
--- a/README.md
+++ b/README.md
@@ -186,6 +186,10 @@ In file.md:
 
 By default, relative links that point to non-existent files (or files that are not being uploaded in the current batch) will result in an error. To ignore these errors and keep the links as they are, use the `--ignore-relative-link-errors` flag.
 
+## Code blocks
+
+By default, line numbers are disabled in Confluence code blocks for cleaner output. To render line numbers alongside your code, pass the `--enable-line-numbers` flag.
+
 ## Directory arguments
 
 ### Uploading Folders Recursively
diff --git a/mdfluence/__main__.py b/mdfluence/__main__.py
index ca560b0..83b8867 100644
--- a/mdfluence/__main__.py
+++ b/mdfluence/__main__.py
@@ -245,6 +245,12 @@ def get_parser():
         help="disable conversion of :shortcode: emoji to Unicode characters",
     )
 
+    parser.add_argument(
+        "--enable-line-numbers",
+        action="store_true",
+        help="enable line numbers in Confluence code blocks",
+    )
+
     parser.add_argument(
         "--render-diagrams",
         action="store_true",
@@ -710,6 +716,7 @@ def collect_pages_to_upload(args):
                 mmdc_path=args.mmdc_path,
                 plantuml_path=args.plantuml_path,
                 title_prefix=args.prefix,
+                enable_line_numbers=args.enable_line_numbers,
             )
         )
 
@@ -743,6 +750,7 @@ def collect_pages_to_upload(args):
                     mmdc_path=args.mmdc_path,
                     plantuml_path=args.plantuml_path,
                     title_prefix=args.prefix,
+                    enable_line_numbers=args.enable_line_numbers,
                 )
             else:
                 try:
@@ -761,6 +769,7 @@ def collect_pages_to_upload(args):
                             mmdc_path=args.mmdc_path,
                             plantuml_path=args.plantuml_path,
                             title_prefix=args.prefix,
+                            enable_line_numbers=args.enable_line_numbers,
                         )
                     )
                 except FileNotFoundError:
diff --git a/mdfluence/confluence_renderer.py b/mdfluence/confluence_renderer.py
index 0bb4415..e3f248d 100644
--- a/mdfluence/confluence_renderer.py
+++ b/mdfluence/confluence_renderer.py
@@ -134,10 +134,12 @@ def __init__(
         render_diagrams=False,
         mmdc_path=None,
         plantuml_path=None,
+        enable_line_numbers=False,
     ):
         super().__init__(escape=False)
         self.strip_header = strip_header
         self.remove_text_newlines = remove_text_newlines
+        self.enable_line_numbers = enable_line_numbers
         self.attachments = list()
         self.title = None
         self.enable_relative_links = enable_relative_links
@@ -274,7 +276,8 @@ def block_code(self, code, info=None):
         if info is not None:
             lang_parameter = self.parameter(name="language", value=info)
             root_element.append(lang_parameter)
-        root_element.append(self.parameter(name="linenumbers", value="true"))
+        linenumbers_value = "true" if self.enable_line_numbers else "false"
+        root_element.append(self.parameter(name="linenumbers", value=linenumbers_value))
         root_element.append(self.plain_text_body(code))
         return root_element.render()
 
diff --git a/mdfluence/document.py b/mdfluence/document.py
index 8dc3774..50ed1ff 100644
--- a/mdfluence/document.py
+++ b/mdfluence/document.py
@@ -131,6 +131,7 @@ def get_pages_from_directory(
     mmdc_path: str | None = None,
     plantuml_path: str | None = None,
     title_prefix: str | None = None,
+    enable_line_numbers: bool = False,
 ) -> List[Page]:
     """
     Collect a list of markdown files recursively under the file_path directory.
@@ -251,6 +252,7 @@ def get_pages_from_directory(
                 mmdc_path=mmdc_path,
                 plantuml_path=plantuml_path,
                 title_prefix=title_prefix,
+                enable_line_numbers=enable_line_numbers,
             )
             processed_page.parent_title = parent_page_title
             processed_pages.append(processed_page)
@@ -275,6 +277,7 @@ def get_page_data_from_file_path(
     mmdc_path: str | None = None,
     plantuml_path: str | None = None,
     title_prefix: str | None = None,
+    enable_line_numbers: bool = False,
 ) -> Page:
     if not isinstance(file_path, Path):
         file_path = Path(file_path)
@@ -299,6 +302,7 @@ def get_page_data_from_file_path(
         mmdc_path=mmdc_path,
         plantuml_path=plantuml_path,
         title_prefix=title_prefix,
+        enable_line_numbers=enable_line_numbers,
     )
 
     if not page.title:
@@ -320,6 +324,7 @@ def get_page_data_from_lines(
     mmdc_path: str | None = None,
     plantuml_path: str | None = None,
     title_prefix: str | None = None,
+    enable_line_numbers: bool = False,
 ) -> Page:
     frontmatter = get_document_frontmatter(markdown_lines)
     if "frontmatter_end_line" in frontmatter:
@@ -339,6 +344,7 @@ def get_page_data_from_lines(
         mmdc_path=mmdc_path,
         plantuml_path=plantuml_path,
         title_prefix=title_prefix,
+        enable_line_numbers=enable_line_numbers,
     )
 
     if "title" in frontmatter:
@@ -366,6 +372,7 @@ def parse_page(
     mmdc_path: str | None = None,
     plantuml_path: str | None = None,
     title_prefix: str | None = None,
+    enable_line_numbers: bool = False,
 ) -> Page:
     markdown_text = "".join(markdown_lines)
 
@@ -385,6 +392,7 @@ def parse_page(
         render_diagrams=render_diagrams,
         mmdc_path=mmdc_path,
         plantuml_path=plantuml_path,
+        enable_line_numbers=enable_line_numbers,
     )
     confluence_mistune = mistune.Markdown(renderer=renderer)
     for plugin in [
diff --git a/test_package/functional/result.xml b/test_package/functional/result.xml
index a93e555..44290d7 100644
--- a/test_package/functional/result.xml
+++ b/test_package/functional/result.xml
@@ -96,7 +96,7 @@ and code blocks:</p>
 <li>This is the second list item.</li>
 </ol>
 <p>Here's some example code:</p>
-<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">true</ac:parameter>
+<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">false</ac:parameter>
 <ac:plain-text-body><![CDATA[return shell_exec("echo $input | $markdown_script");]]></ac:plain-text-body>
 </ac:structured-macro>
 </blockquote>
@@ -205,7 +205,7 @@ inside a list item.</p>
 to be indented <em>twice</em> -- 8 spaces or two tabs:</p>
 <ul>
 <li><p>A list item with a code block:</p>
-<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">true</ac:parameter>
+<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">false</ac:parameter>
 <ac:plain-text-body><![CDATA[<code goes here>]]></ac:plain-text-body>
 </ac:structured-macro>
 </li>
@@ -218,11 +218,11 @@ in both <code>&lt;pre&gt;</code> and <code>&lt;code&gt;</code> tags.</p>
 <p>To produce a code block in Markdown, simply indent every line of the
 block by at least 4 spaces or 1 tab.</p>
 <p>This is a normal paragraph:</p>
-<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">true</ac:parameter>
+<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">false</ac:parameter>
 <ac:plain-text-body><![CDATA[This is a code block.]]></ac:plain-text-body>
 </ac:structured-macro>
 <p>Here is an example of AppleScript:</p>
-<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">true</ac:parameter>
+<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">false</ac:parameter>
 <ac:plain-text-body><![CDATA[tell application "Foo"
     beep
 end tell]]></ac:plain-text-body>
@@ -234,7 +234,7 @@ are automatically converted into HTML entities. This makes it very
 easy to include example HTML source code using Markdown -- just paste
 it and indent it, and Markdown will handle the hassle of encoding the
 ampersands and angle brackets. For example, this:</p>
-<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">true</ac:parameter>
+<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">false</ac:parameter>
 <ac:plain-text-body><![CDATA[<div class="footer">
     &copy; 2004 Foo Corporation
 </div>]]></ac:plain-text-body>
@@ -242,7 +242,7 @@ ampersands and angle brackets. For example, this:</p>
 <p>Regular Markdown syntax is not processed within code blocks. E.g.,
 asterisks are just literal asterisks within a code block. This means
 it's also easy to use Markdown to write about Markdown's own syntax.</p>
-<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">true</ac:parameter>
+<ac:structured-macro ac:name="code"><ac:parameter ac:name="linenumbers">false</ac:parameter>
 <ac:plain-text-body><![CDATA[tell application "Foo"
     beep
 end tell
diff --git a/test_package/functional/test_full_rendering.py b/test_package/functional/test_full_rendering.py
index e021df7..b3628d4 100644
--- a/test_package/functional/test_full_rendering.py
+++ b/test_package/functional/test_full_rendering.py
@@ -22,3 +22,16 @@ def test_full_document(script_loc):
 
     assert page.body == result_data
     assert page.title == "Markdown: Syntax"
+
+
+def test_full_document_with_line_numbers(script_loc):
+    markdown_path = script_loc.join("test.md")
+
+    page = document.get_page_data_from_file_path(
+        markdown_path, enable_line_numbers=True
+    )
+
+    # All code blocks should have linenumbers set to true
+    assert '<ac:parameter ac:name="linenumbers">true</ac:parameter>' in page.body
+    assert '<ac:parameter ac:name="linenumbers">false</ac:parameter>' not in page.body
+    assert page.title == "Markdown: Syntax"
diff --git a/test_package/unit/test_renderer.py b/test_package/unit/test_renderer.py
index f469a5a..2fb872e 100644
--- a/test_package/unit/test_renderer.py
+++ b/test_package/unit/test_renderer.py
@@ -132,7 +132,7 @@ def test_renderer_block_code():
     test_code = "this is a piece of code"
     test_markup = (
         '<ac:structured-macro ac:name="code">'
-        '<ac:parameter ac:name="linenumbers">true</ac:parameter>\n'
+        '<ac:parameter ac:name="linenumbers">false</ac:parameter>\n'
         "<ac:plain-text-body><![CDATA[this is a piece of code]]></ac:plain-text-body>\n"
         "</ac:structured-macro>\n"
     )
@@ -148,7 +148,7 @@ def test_renderer_block_code_with_language():
     test_markup = (
         '<ac:structured-macro ac:name="code">'
         '<ac:parameter ac:name="language">whitespace</ac:parameter>\n'
-        '<ac:parameter ac:name="linenumbers">true</ac:parameter>\n'
+        '<ac:parameter ac:name="linenumbers">false</ac:parameter>\n'
         "<ac:plain-text-body><![CDATA[this is a piece of code]]></ac:plain-text-body>\n"
         "</ac:structured-macro>\n"
     )
@@ -158,6 +158,36 @@ def test_renderer_block_code_with_language():
     assert renderer.block_code(test_code, info=test_language) == test_markup
 
 
+def test_renderer_block_code_with_line_numbers():
+    test_code = "this is a piece of code"
+    test_markup = (
+        '<ac:structured-macro ac:name="code">'
+        '<ac:parameter ac:name="linenumbers">true</ac:parameter>\n'
+        "<ac:plain-text-body><![CDATA[this is a piece of code]]></ac:plain-text-body>\n"
+        "</ac:structured-macro>\n"
+    )
+
+    renderer = ConfluenceRenderer(enable_line_numbers=True)
+
+    assert renderer.block_code(test_code) == test_markup
+
+
+def test_renderer_block_code_with_language_and_line_numbers():
+    test_code = "this is a piece of code"
+    test_language = "python"
+    test_markup = (
+        '<ac:structured-macro ac:name="code">'
+        '<ac:parameter ac:name="language">python</ac:parameter>\n'
+        '<ac:parameter ac:name="linenumbers">true</ac:parameter>\n'
+        "<ac:plain-text-body><![CDATA[this is a piece of code]]></ac:plain-text-body>\n"
+        "</ac:structured-macro>\n"
+    )
+
+    renderer = ConfluenceRenderer(enable_line_numbers=True)
+
+    assert renderer.block_code(test_code, info=test_language) == test_markup
+
+
 def test_renderer_header_sets_title():
     test_header = "this is a header"
     renderer = ConfluenceRenderer()