diff --git a/bundler/lib/bundler/settings.rb b/bundler/lib/bundler/settings.rb
index 81f1857eec76..8c06593bcfe8 100644
--- a/bundler/lib/bundler/settings.rb
+++ b/bundler/lib/bundler/settings.rb
@@ -59,6 +59,7 @@ class Settings
       bin
       cache_path
       console
+      default_cli_command
       gem.ci
       gem.github_username
       gem.linter
diff --git a/bundler/lib/bundler/settings/validator.rb b/bundler/lib/bundler/settings/validator.rb
index 9aa1627fb2e2..093e9c2b62d9 100644
--- a/bundler/lib/bundler/settings/validator.rb
+++ b/bundler/lib/bundler/settings/validator.rb
@@ -74,6 +74,13 @@ def self.validate!(key, value, settings)
           fail!(key, value, "`#{other_key}` is current set to #{other_setting.inspect}", "the `#{conflicting.join("`, `")}` groups conflict")
         end
       end
+
+      rule %w[default_cli_command], "default_cli_command must be either 'install' or 'cli_help'" do |key, value, settings|
+        valid_values = %w[install cli_help]
+        if !value.nil? && !valid_values.include?(value.to_s)
+          fail!(key, value, "must be one of: #{valid_values.join(", ")}")
+        end
+      end
     end
   end
 end
diff --git a/bundler/spec/bundler/settings_spec.rb b/bundler/spec/bundler/settings_spec.rb
index 592db81e9b90..bf2b3fddb890 100644
--- a/bundler/spec/bundler/settings_spec.rb
+++ b/bundler/spec/bundler/settings_spec.rb
@@ -351,4 +351,28 @@
       expect(settings["mirror.https://rubygems.org/"]).to eq("http://example-mirror.rubygems.org")
     end
   end
+
+  describe "default_cli_command validation" do
+    it "accepts 'install' as a valid value" do
+      expect { settings.set_local("default_cli_command", "install") }.not_to raise_error
+    end
+
+    it "accepts 'cli_help' as a valid value" do
+      expect { settings.set_local("default_cli_command", "cli_help") }.not_to raise_error
+    end
+
+    it "rejects invalid values" do
+      expect { settings.set_local("default_cli_command", "invalid") }.to raise_error(
+        Bundler::InvalidOption,
+        /Setting `default_cli_command` to "invalid" failed:\n - default_cli_command must be either 'install' or 'cli_help'\n - must be one of: install, cli_help/
+      )
+    end
+
+    it "rejects nil values" do
+      expect { settings.set_local("default_cli_command", nil) }.to raise_error(
+        Bundler::InvalidOption,
+        /Setting `default_cli_command` to nil failed:\n - default_cli_command must be either 'install' or 'cli_help'\n - must be one of: install, cli_help/
+      )
+    end
+  end
 end