The squadron was formed in February 1917 and saw action in the First World War as a night bomber squadron. An aircraft from 100 Sqn was the last aircraft to return to base in the war, returning on the night before the Armistice. At the start of the Second World War, the unit operated Vildebeest in Singapore. The Sqn lost most of its aircraft and replacements were not forthcoming and as the Japanese advanced, most personnel became prisoners of war. In December 1942 the squadron reformed at RAF Grimsby with Lancasters which it operated for the rest of the war. Post war the unit operated Lincolns, Canberras, Victors, back to Canberras, and finally Hawks. It was disbanded in March 2022 ending 105 years of service.