The Germany international midfielder posted footage on Tuesday of him returning to begin his rehabilitation at the club's Etihad Campus.
Gundogan suffered cruciate ligament damage in the home victory over Watford last month and had been allowed to rest up over Christmas following surgery.
But the 26-year-old appears to be hitting the comeback trail well and he can be seen using a weighted leg curl machine to build up the muscle.
Gundogan has quickly proved a popular member of Pep Guardiola's squad following his £20m move from Borussia Dortmund last summer.
The playmaker was forced to miss the start of the season due to a dislocated knee he suffered while playing basketball with friends but showed his value to the Citizens by scoring five times in 20 appearances - the highest scoring return in his career so far.