Di Matteo, whose side missed out on the automatic promotion spots, guided Dons to five wins from six matches in the month.
He held off competition from Leicester boss Pearson, Ferguson at Peterborough and Grayson of Leeds.
"We had many games in March which cost us, but once we got that behind us April was a better month for us," he told Sky Sports News.
"The players have given everything and worked very hard.
"We have a very good group of players and I think we have a good chance in the play-offs."