The Sky Blues have been tracking the Frenchman – who is currently away with Les Bleus at the World Cup – and even came close to snapping him up in a double deal with midfielder Fernando during January.
However the move fell through as City baulked at the fees involved at the time, but the Brazilian enforcer has since switched to the Etihad Stadium.
Now Mangala looks set to follow, with Porto having accepted a £32m bid from the Premier League champions.
With personal terms understood to have been agreed over the winter, the 23-year-old’s official arrival looks to be all but a formality.
Manuel Pellegrini is known to have made securing a partner for captain Vincent Kompany a priority after relying on the shaky Martin Demichelis for the latter half of 2013/14.
Chelsea are also interested in Mangala, but having signed Kurt Zouma from Saint Etienne, they may opt against matching City’s large offer.
Manchester United are another side to have been linked with the defender.