Gleeson's 30-yard screamer into the top corner of the net just before half-time gave the Dons the lead in the first-ever meeting between the two clubs formed out of the old Wimbledon FC.
Jack Midson's diving header brought AFC Wimbledon level before Otsemobor's flick in injury-time settled the FA Cup second-round tie in favour of the Milton Keynes club.
Following the 2-1 win at stadium:mk, manager Karl Robinson said: "Both players have written themselves into MK Dons folklore forever and a day.
"This was an historic occasion and those are the pictures we will look up in years to come, they will be up on our walls."
MK Dons have been handed an away tie against Sheffield Wednesday in the third round, a game Robinson is looking forward to for personal reasons as well as footballing ones.
"I love the FA Cup and I love being in it," he said. "Hillsborough is a great place to go, especially for me, being a Liverpool fan from Liverpool, it's always a tie I enjoy.
"I always go and have a minute to myself while I'm there to remember [the 96 Liverpool fans that died in the Hillsborough tragedy in April 1989], I always have done.
"It's quite fitting for me to go there in the FA Cup as a manager, it'll give me a chance to show my respect once again."