UB-50 surrendered on 16 January 1919 with the remainder of the Pola Flotilla following an order by Admiral Reinhard Scheer to return to port.

Like all Type UB III submarines, UB-50 carried 10 torpedoes and was armed with an 8.8 cm (3.5 in) SK L/30 deck gun.

[7] Four days later, UB-50 finally encountered and sank a merchant, this being the 3,611 GRT British Polar Prince, carrying coal for Malta.

[12] Four days later, the 296 GRT Italian sailboat Ciro was scuttled after being hit by UB-50,[13] the last ship she would sink before returning to base.

SM UB-50 began her second patrol with the sinking of the Marc Fraissinet, a 3,060 GRT French steamer carrying wood, munitions, and hay to Bizerte.

[14] Later that day UB 50 encountered the Senegal, an 845 GRT Italian steamer, sinking her off the coast of Algeria with no casualties.

[17] Four days later, the submarine found her last target of her second patrol, the 2,774 GRT American steamer Rizal, which sank 9 nautical miles (17 km; 10 mi) from Cape Cavallo.

[19] She sank the 8,293 GRT British steamer City of Lucknow two days later 50 nautical miles (93 km; 58 mi) northeast of the Cani Rocks.

[20] On Christmas Day, 1917, UB-50 sank the Sant’ Antonio, an 843 GRT Italian sailing vessel, by gunfire near Bizerte.

[21] On New Year's Day, 1918, the Egyptian Transport, a 4,648 GRT British steamer, was damaged during an attack by UB-50, which killed five men.

[29][30] UB-50 began her fifth war patrol by damaging the 3,926 GRT British steamer Elswick Grange carrying coal off the coast of Oran, killing one.

[32] On that same day, she came upon the 168 GRT Danish three-masted iron-hulled schooner Kirstine Jesen, sinking after being fired upon from UB-50's deck gun with no deaths.

[38] On her sixth patrol, UB-50 encountered the Imber, a 2,514 GRT British steamer and torpedoed her south of Cape St. Maria di Leuca, though she survived.

[39] Three days later, UB-50 sank the War Swallow, a 5,216 GRT British merchant ship carrying coal from the River Tyne to Port Said.

[40] Another three days passed before UB-50 found her next target, the Italian steamer Adria 1, a ship carrying cotton from Palermo to Tunis.