Guardiola oversaw wins over West Ham, Swansea City and Bournemouth, scoring eight times and conceding just once.
The 46-year-old therefore avoids failing to win the award in his debut Premier League season.
Chelsea manager Antonio Conte had been dominant, winning in three of the preceding four months.
Guardiola beat fellow nominees Conte, Jose Mourinho and Tony Pulis to the award. It is the first time a City boss has claimed the accolade since August 2015, when Manuel Pellegrini came out on top.