SM UB-124 was a German Type UB III submarine or U-boat in the German Imperial Navy () during World War I. She was commissioned into the German Imperial Navy on 22 April 1918 as SM UB-124.
UB-124 was sunk on 20 July 1918 by , , , and more than 30 patrol craft at .
She was built by AG Weser of Bremen and, following just under a year of construction, launched at Bremen on 19 March 1918. UB-124 was commissioned later the same year under the command of Oblt.z.S. Hans Oscar Wutsdorff. Like all Type UB III submarines, UB-124 carried ten torpedoes and was armed with an deck gun. UB-124 would carry a crew of up to three officers and 31 men and had a cruising range of . UB-124 had a displacement of while surfaced and when submerged. Her engines enabled her to travel at when surfaced and when submerged.