Former Dons striker Sam Baldock twice put the Robins ahead, but fine second-half finishes from Patrick Bamford and substitute Samir Carruthers maintained the Dons' unbeaten record.
Aden Flint headed against the post for City before Baldock put them ahead, controlling Bobby Reid's pass in the box to lash a fine strike into the top corner.
Bamford equalised for the Dons seven minutes after the break when he raced on to Luke Chadwick's pass and drilled a clinical shot inside the far post.
Baldock restored City's lead in the 66th minute when he ran clear on to a long punt and drilled the ball low past David Martin for his fifth goal of the season.
But Carruthers made it it 2-2 just three minutes later, firing an excellent first-time shot into the top corner from substitute Dele Alli's pass.
O'Driscoll said: "It was frustrating to draw, but you only get better when you make mistakes - we were guilty of that at times.
"We worked really hard, defensively we looked more sound than we have in the last two or three games and we are always going to score goals.
"MK Dons are a good team, they open up people, it's a big pitch and they use it to its maximum, but we're just beginning.
"Sam is a goal-scorer. When I first walked through the door he was playing wide and sometimes he'll have to do that in this division just with the nature of the squad we've got.
"But if we stick him down the middle he's had chances in every game he's played and he's probably missed easier chances than he scored here.
"If we can keep him fit and keep providing him with chances then he'll end up being one of the top goal-scorers in the division.
"We've just got to make sure that we can keep enough clean sheets as well for it to get us three points."