Skipper Keith Andrews' first goal for the club and McLeod's double earned Dons their third straight win, while Tommy Mooney replied for Wanderers, who had Tommy Doherty sent off late on.
The Dons started brightly and Clive Platt headed Jon-Paul McGovern's teasing cross straight at Jamie Young from 10 yards inside the first minute.
But tempers flared in the seventh minute when Wycombe midfielder Matt Bloomfield was forced off unconscious after being shoved into the advertising boards by Gareth Edds as the pair contested a tackle near the touchline.
Livid Wanderers skipper Mooney was shown a yellow card for protesting too vehemently in the fracas that followed.
Wycombe appeared rattled from the incident and Lloyd Dyer volleyed a good chance straight at Wanderers' keeper Young before Andrews put the fired-up Dons in front in the 17th minute.
Andrews clipped Dean Lewington's low cross goal-wards at the near post, and the ball deflected off the unlucky Mike Williamson and past Young for Andrews' first goal for the Dons.
Will Antwi went close to equalising for Wycombe in the 24th minute but his close range header from substitute Stefan Oakes deep free-kick was too close to Milton Keynes goalkeeper Lee Harper at his near post, before McLeod doubled the Dons' lead from the penalty spot a minute later.
McLeod picked himself up after he had been chopped down in the box by Williamson to coolly slot his 15th goal of the season straight down the middle from 12 yards.
Yet Mooney handed Wanderers a lifeline when his composed close range finish made it 2-1 in the 31st minute. Jermaine Easter seized upon Dons defender Drissa Diallo's error to race clear into the box, and he crossed perfectly for the unmarked Mooney to control the ball before despatching it low past Harper from 10 yards.
Wycombe pressed for an equaliser after the break and lively substitute Ikechi Anya's 12-yard angled drive was saved well by Harper at his near post in the 67th minute.
But the Dons threatened on the counter-attack and Lewington crashed a swerving 25-yard drive against the bar in the 73rd minute.
Doherty picked up his second booking in the 80th minute - both for dissent - but Wycombe's 10-men still pressed and the unmarked Easter headed against the post in the 83rd minute.
But McLeod grabbed his 16th goal of the season with an exquisite 25-yard curler to seal the win for the Dons three minutes from the end.