Oakwood pipped Redbridge Jewish Care A to the crown after the east Londoners slipped to defeat in their final match of the season against Hendon United.
And Blank described the accolade as a "fairytale ending" following a lengthy spell with the club, first as a player and then manager.
“For me to go out with title and be awarded joint manager of the year as my final act - it really is a fairytale ending for me," he added.
"It's set me up brilliantly for the summer. Believe it or not we are already planning next season - I think we're going to be even stronger."
Avi Garson of Faithfold B is the league's Young Player of the Year, while James Harpin, who led Maccabi London Lions B to the runners-up spot in Division One, received the Safe Hands awards for best goalkeeper.
All of this season's award winners will be confirmed in early June.
