4th (Central Ontario) Battalion, CEF was an infantry battalion raised as part of the Canadian Expeditionary Force for service during the First World War. Raised in Canada in September 1914, the battalion sailed to the United Kingdom within weeks of its establishment. After a short period of training it was committed to the fighting on the Western Front, remaining in France and Belgium until the war ended. It returned to Canada in mid-1919 and after its personnel had been demobilized, the battalion was subsequently disbanded in 1920.