Howe has overseen an incredible change in fortunes since making his return to Dean Court in the middle of October with nine wins and three draws in all competitions since then.
His side won three from five in November, adding in an FA Cup victory over Dagenham & Redbridge, and they have moved away from the bottom end of the table to lie ninth, just four points outside the play-off places.
Howe beat off competition from MK Dons manager Karl Robinson and Brentford's Uwe Rosler to win the award, and he said: "This is all down to the team.
"Ever since we have come back in the players have been excellent as has the staff around me, and the supporters have also more than played their part in that run we've been on.
"(Christmas) is a very vital time for us - we've got a lot of games as have the other teams, but we're still in catch-up mode at the moment so we've still got a lot of work to do to get up to the top two and the top six, so these games will be pivotal against our rivals at the top end of the table."
Player of the month honours went to Orient's veteran striker Kevin Lisbie, who scored five goals in five League One games with doubles against Shrewsbury and Portsmouth.