Carlo Ancelotti, Sean Dyche, Ole Gunnar Solskjaer and Dean Smith were nominated for December's Barclays Manager of the Month award after standout results at the end of 2020.
The public vote was combined with those of a panel of football experts to decide the winner.
The Italian led Everton to four consecutive victories in an unbeaten December, including a 1-0 home win over Chelsea. They earned three clean sheets during that run, with Ancelotti responding to injury problems at full-back by fielding four centre-backs across the defence with great success.
Dyche took Burnley out of the relegation zone with an impressive upturn in form last month. The Clarets, who only suffered one narrow defeat at Leeds United, claimed their first ever PL win over Arsenal and were unbeaten against high-flying Everton and Aston Villa.
Solskjaer’s men won four of their six matches at the end of 2020 to close in on leaders Liverpool, only being denied victory by title rivals Manchester City and Leicester City. Man Utd also claimed comeback wins at West Ham United and Sheffield United and put six past Leeds at home.
Aston Villa finished the year in fifth place after an unbeaten December. Smith’s team scored three goals in successive matches against West Bromwich Albion and Crystal Palace and had a run of four straight clean sheets, only conceding once at Chelsea.