Khusanov, 22, joined City from RC Lens in January 2025 and made 21 league appearances last season, 15 of them starts, despite his deal at the Etihad only running until 2029 before this extension.
According to The Athletic, the Uzbekistan international is expected to commit his long-term future to the club in the coming days.
Doku, meanwhile, is also poised to sign fresh terms, with the winger's representatives said to have been handling the extension while he was away with Belgium at the World Cup. His current contract runs until 2028, but the new deal would extend that by a further three years to match Khusanov's.
The moves follow the confirmation of a new contract for Phil Foden, announced on the same day, as City continue their efforts to secure the futures of several of their most important players.
Manchester City finished second in the Premier League last season under new head coach Enzo Maresca, who succeeded Pep Guardiola at the end of the campaign, and the club appears determined to build for the future around a core of contracted, homegrown and long-serving talent as it enters a new managerial era.
Khusanov quickly established himself as a key defensive option following injuries to Ruben Dias and Josko Gvardiol last season, while Doku has continued to develop into one of the Premier League's most dangerous wide players since joining the club. City are also reported to be closing in on a separate extension for Josko Gvardiol, despite continued interest in the Croatian from clubs in Germany and Spain.
Both Khusanov and Doku are seen internally as central figures in City's rebuild under Maresca, with the club keen to avoid the uncertainty that has affected the futures of some of its more senior players this summer, most notably Rodri, who remains hesitant over signing fresh terms amid reported interest from Real Madrid.
Securing Khusanov and Doku on extended deals would give City a settled core to build around as they look to respond to a trophy-light campaign by the club's recent standards.