Guardiola, who led City to the Premier League, FA Cup and Champions League trophies across the season, was on a three-man shortlist for the prestigious honour.
He beat off competition from Simone Inzaghi, who led Inter to Champions League final against City, as well as Luciano Spalletti, who won the Serie A title with Napoli.
In winning the Champions League, Guardiola became the first manager to win two European Trebles in the men’s game.
It helped him surpass the eight other bosses who have won one European men’s Treble, including Celtic’s Jock Stein, Stefan Kovacs of Ajax, Guus Hiddink with PSV, Sir Alex Ferguson with Manchester United, Jose Mourinho with Inter, Bayern Munich’s Jupp Heynckes, Luis Enrique of Barcelona and Hansi Flick of Bayern Munich.