The former Chesterfield man broke the deadlock when he tapped in from close range in the 20th minute and sealed all three points with a fine strike with 12 minutes left.
In between 19-year-old Sam Baldock celebrated his new two-year deal in style when he smashed home from 20 yards. The hosts were dominant throughout and their first came when Leven pounced on a rebound from Aaron Wilbraham's powerful header.
In return Yeovil rattled the bar when Gary Roberts cut in well from the left and was afforded time to shoot, but that was their best effort all afternoon.
Dons took over in the second half and Baldock got his third goal of the season when he wriggled free from Terrell Forbes and fired in at the near post.
And Leven put the game to bed when he finished off a superb passing move by converting Florian Sturm's low cross as the Dons cruised to victory.