SM UC-77 was a German Type UC II minelaying submarine or U-boat in the German Imperial Navy (German: Kaiserliche Marine) during World War I. The U-boat was ordered on 12 January 1916 and was launched on 2 December 1916. She was commissioned into the German Imperial Navy on 29 December 1916 as SM UC-77. In 13 patrols UC-77 was credited with sinking 34 ships, either by torpedo or by mines laid. UC-77 was mined and sunk off Flanders on 14 July 1918.