diff --git a/changelogs/unreleased/47050-quick-actions-case-insensitive.yml b/changelogs/unreleased/47050-quick-actions-case-insensitive.yml
new file mode 100644
index 00000000000..176aba627b9
--- /dev/null
+++ b/changelogs/unreleased/47050-quick-actions-case-insensitive.yml
@@ -0,0 +1,5 @@
+---
+title: Make quick commands case insensitive
+merge_request: 19614
+author: Jan Beckmann
+type: fixed
diff --git a/lib/gitlab/quick_actions/extractor.rb b/lib/gitlab/quick_actions/extractor.rb
index 075ff91700c..30c6806b68e 100644
--- a/lib/gitlab/quick_actions/extractor.rb
+++ b/lib/gitlab/quick_actions/extractor.rb
@@ -39,7 +39,7 @@ module Gitlab
         content.delete!("\r")
         content.gsub!(commands_regex) do
           if $~[:cmd]
-            commands << [$~[:cmd], $~[:arg]].reject(&:blank?)
+            commands << [$~[:cmd].downcase, $~[:arg]].reject(&:blank?)
             ''
           else
             $~[0]
@@ -102,14 +102,14 @@ module Gitlab
               # /close
 
               ^\/
-              (?<cmd>#{Regexp.union(names)})
+              (?<cmd>#{Regexp.new(Regexp.union(names).source, Regexp::IGNORECASE)})
               (?:
                 [ ]
                 (?<arg>[^\n]*)
               )?
               (?:\n|$)
             )
-        }mx
+        }mix
       end
 
       def perform_substitutions(content, commands)
@@ -120,7 +120,7 @@ module Gitlab
         end
 
         substitution_definitions.each do |substitution|
-          match_data = substitution.match(content)
+          match_data = substitution.match(content.downcase)
           if match_data
             command = [substitution.name.to_s]
             command << match_data[1] unless match_data[1].empty?
diff --git a/lib/gitlab/quick_actions/substitution_definition.rb b/lib/gitlab/quick_actions/substitution_definition.rb
index 032c49ed159..688056e5d73 100644
--- a/lib/gitlab/quick_actions/substitution_definition.rb
+++ b/lib/gitlab/quick_actions/substitution_definition.rb
@@ -15,7 +15,7 @@ module Gitlab
         return unless content
 
         all_names.each do |a_name|
-          content.gsub!(%r{/#{a_name} ?(.*)$}, execute_block(action_block, context, '\1'))
+          content.gsub!(%r{/#{a_name} ?(.*)$}i, execute_block(action_block, context, '\1'))
         end
         content
       end
diff --git a/spec/lib/gitlab/quick_actions/extractor_spec.rb b/spec/lib/gitlab/quick_actions/extractor_spec.rb
index f7c288f2393..0166f6c2ee0 100644
--- a/spec/lib/gitlab/quick_actions/extractor_spec.rb
+++ b/spec/lib/gitlab/quick_actions/extractor_spec.rb
@@ -182,6 +182,14 @@ describe Gitlab::QuickActions::Extractor do
       expect(msg).to eq "hello\nworld"
     end
 
+    it 'extracts command case insensitive' do
+      msg = %(hello\n/PoWer @user.name %9.10 ~"bar baz.2"\nworld)
+      msg, commands = extractor.extract_commands(msg)
+
+      expect(commands).to eq [['power', '@user.name %9.10 ~"bar baz.2"']]
+      expect(msg).to eq "hello\nworld"
+    end
+
     it 'does not extract noop commands' do
       msg = %(hello\nworld\n/reopen\n/noop_command)
       msg, commands = extractor.extract_commands(msg)
@@ -206,6 +214,14 @@ describe Gitlab::QuickActions::Extractor do
       expect(msg).to eq "hello\nworld\nthis is great? SHRUG"
     end
 
+    it 'extracts and performs substitution commands case insensitive' do
+      msg = %(hello\nworld\n/reOpen\n/sHRuG this is great?)
+      msg, commands = extractor.extract_commands(msg)
+
+      expect(commands).to eq [['reopen'], ['shrug', 'this is great?']]
+      expect(msg).to eq "hello\nworld\nthis is great? SHRUG"
+    end
+
     it 'extracts and performs substitution commands with comments' do
       msg = %(hello\nworld\n/reopen\n/substitution wow this is a thing.)
       msg, commands = extractor.extract_commands(msg)