Pioli won votes from 33 of his 46 colleagues at a ceremony at the Italian Soccer Federation’s Coverciano base near Florence.
He succeeds Tottenham Hotspur boss Antonio Conte, who had led Inter to the Serie A title the previous season.
The Panchina d’Oro (Golden Bench) is awarded to the best coach in Serie A for the previous season by a jury of peers.
Juventus boss Massimiliano Allegri and Tottenham Hotspur manager Antonio Conte share the record for most Golden Bench awards with four apiece.
“I’m emotional,” Pioli, who dedicated his prize to his players, backroom staff and the entire setup at Milan, said.
“When I see again what we did last year, the emotions come back.”
Milan are currently fourth in Serie A, 18 points behind leaders Napoli, who maintained their colossal 15-point lead over second-placed Inter, with a 2-0 at Sassuolo during a weekend in which all the top flight’s big guns notched victories.
Inter are on 47 points from 23 games thanks to a 3-1 triumph over Udinese at San Siro.
AS Roma are three points further back in third after beating Hellas Verona 1-0 at home.
Champions AC Milan, who also have 44 points, beat the Monza club of their ex-president Silvio Berlusconi 1-0, too.
Juventus, who have had 15 points deduced due to financial irregularities, are seventh with 32 points following a 2-0 win at Spezia.
ANSA