UB-2 was ordered in October 1914 and was laid down at the Germaniawerft shipyard in Kiel in November. UB-2 was a little more than in length and displaced between , depending on whether surfaced or submerged. She carried two torpedoes for her two bow torpedo tubes and was also armed with a deck-mounted machine gun. She was launched and commissioned as SM UB-2 in February 1915.