UB-7 was ordered in October 1914 and was laid down at the AG Weser shipyard in Bremen in November. UB-7 was a little under 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. UB-7 was originally one of a pair of UB I boats sent to the Austro-Hungarian Navy to replace an Austrian pair to be sent to the Dardanelles, and was broken into sections and shipped by rail to Pola in March 1915 for reassembly. She was launched in April and commissioned as SM UB-7 in the German Imperial Navy in May when the Austrians opted out of the agreement.