Mangala spent the second half of last season out on loan at Everton, where he made just two appearances before suffering a knee injury.
The 27-year-old was thought to be viewed as surplus to requirements by Guardiola, but he will be available for Premier League games until at least January having been named in the Spaniard's roster.
Mangala is expected to remain behind Vincent Kompany, Aymeric Laporte, Nicolas Otamendi and John Stones in the pecking order at the Etihad Stadium, but Guardiola has included the Frenchman as extra cover at centre-back.
The former Porto and Valencia man deputised for the injured Stones last season, featuring in eight unbeaten games for the eventual champions between November and Christmas.
Claudio Bravo, Kevin De Bruyne and Danilo are all named in the 25-man squad despite currently being sidelined, while the likes of Phil Foden and Brahim Diaz are automatically eligible as they are under the age of 21.