diff --git a/changelogs/unreleased/37843-ci-trace-ansi-colours-256-bold-have-no-css-due-wrongly-ansi2html-light-color-variant-conversion-feature.yml b/changelogs/unreleased/37843-ci-trace-ansi-colours-256-bold-have-no-css-due-wrongly-ansi2html-light-color-variant-conversion-feature.yml
new file mode 100644
index 00000000000..abf98cd2af4
--- /dev/null
+++ b/changelogs/unreleased/37843-ci-trace-ansi-colours-256-bold-have-no-css-due-wrongly-ansi2html-light-color-variant-conversion-feature.yml
@@ -0,0 +1,5 @@
+---
+title: Fix ANSI 256 bold colors in pipelines job output
+merge_request:
+author:
+type: fixed
diff --git a/lib/gitlab/ci/ansi2html.rb b/lib/gitlab/ci/ansi2html.rb
index 72b75791bbb..e25916528f4 100644
--- a/lib/gitlab/ci/ansi2html.rb
+++ b/lib/gitlab/ci/ansi2html.rb
@@ -234,7 +234,7 @@ module Gitlab
             # Most terminals show bold colored text in the light color variant
             # Let's mimic that here
             if @style_mask & STYLE_SWITCHES[:bold] != 0
-              fg_color.sub!(/fg-(\w{2,}+)/, 'fg-l-\1')
+              fg_color.sub!(/fg-([a-z]{2,}+)/, 'fg-l-\1')
             end
             css_classes << fg_color
           end
diff --git a/spec/lib/gitlab/ci/ansi2html_spec.rb b/spec/lib/gitlab/ci/ansi2html_spec.rb
index 33540eab5d6..05e2d94cbd6 100644
--- a/spec/lib/gitlab/ci/ansi2html_spec.rb
+++ b/spec/lib/gitlab/ci/ansi2html_spec.rb
@@ -120,6 +120,10 @@ describe Gitlab::Ci::Ansi2html do
     expect(convert_html("\e[48;5;240mHello")).to eq('<span class="xterm-bg-240">Hello</span>')
   end
 
+  it "can print 256 xterm fg bold colors" do
+    expect(convert_html("\e[38;5;16;1mHello")).to eq('<span class="xterm-fg-16 term-bold">Hello</span>')
+  end
+
   it "can print 256 xterm bg colors on normal magenta foreground" do
     expect(convert_html("\e[48;5;16;35mHello")).to eq('<span class="term-fg-magenta xterm-bg-16">Hello</span>')
   end