Aaron Wilbraham put the Dons in front in the first half, but the striker was sent off for a second bookable offence after bringing down Oli Johnson on the edge of the box and Martin curled home the resulting free-kick for his 22nd goal of the season.
The Canaries had dominated the early stages, with defender Gary Doherty seeing goal-bound headers blocked by first Mark Carrington and then goalkeeper Willy Gueret in the first seven minutes.
But the Dons weathered the storm and took the lead after 20 minutes when Wilbraham blasted home from close range after a Peter Leven corner had been inadvertently helped on by Norwich defender Russell Martin.
It was all Norwich after that and Gueret had to be at his best again on the hour-mark when he somehow turned away a snap-shot from Grant Holt.
Paul Ince's side, who picked up no fewer than nine bookings, looked like holding on for a surprise win but Martin produced a moment of quality to deny them after Wilbraham had seen red for upending Johnson in the 89th minute.