She was built by AG Weser of Bremen and following just under a year of construction, launched at Bremen on 2 March 1918. UB-123 was commissioned later the same year under the command of Oblt.z.S. Robert Ramm. Like all Type UB III submarines, UB-123 carried 10 torpedoes and was armed with a 10.5 cm (4.13 in) deck gun. UB-123 would carry a crew of up to 3 officer and 31 men and had a cruising range of 7,280 nautical miles (13,480 km; 8,380 mi). UB-123 had a displacement of 512 t (504 long tons) while surfaced and 643 t (633 long tons) when submerged. Her engines enabled her to travel at 13.9 knots (25.7 km/h; 16.0 mph) when surfaced and 7.6 knots (14.1 km/h; 8.7 mph) when submerged.
^Helgason, Guðmundur. "WWI U-boats: UB 123". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 13 February 2009.
^Helgason, Guðmundur. "WWI U-boat commanders: Robert Ramm". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 10 March 2015.
^Helgason, Guðmundur. "Ships hit by UB 123". German and Austrian U-boats of World War I - Kaiserliche Marine - Uboat.net. Retrieved 10 March 2015.