German submarine U-1229 was a Type IXC/40 U-boat built for Nazi Germany's Kriegsmarine during World War II.

The submarine was powered by two MAN M 9 V 40/46 supercharged four-stroke, nine-cylinder diesel engines producing a total of 4,400 metric horsepower (3,240 kW; 4,340 shp) for use while surfaced, two Siemens-Schuckert 2 GU 345/34 double-acting electric motors producing a total of 1,000 shaft horsepower (1,010 PS; 750 kW) for use while submerged.

About three months later she was commissioned into service under the command of Kapitänleutnant Arnim Zinke (Crew 31) in the 31st U-boat Flotilla on 13 January 1944.

After completing training and work-up for deployment, U-1229 was transferred to the 10th U-boat Flotilla for front-line service on 1 August 1944.

The U-boat left Kiel on 13 July 1944 for the first and only war patrol operating unsuccessfully against Allied shipping in the North Atlantic and off the coast of Canada.