While the Dons chalked up a 10th straight victory, nearest rivals Rochford lost at home.
Wimbledon had to work hard for their win, especially in the first half.
Brighton contributed equally to an entertaining 80 minutes and were first to score. Frank Taggart shook off the defence at the back of a lineout 10 metres out and went over in the corner, David McIlwaine kicking a fine conversion.
Wimbledon hit back when scrum half Blane Wilson put the backs away and centre Jack Reville dummied and twisted his way through tackles to score.
Five minutes later Brighton’s wing Alex Basson raced in for their second try.
Then it was the Dons’ turn again – a deft chip by full-back James Moffat put them deep into Brighton’s 22 and two lineouts and two penalties later it was number eight Chris York who bulldozed over.
Moffat’s conversion drew the score level at 12-12.
Ten minutes on a second conversion made it 19-12 after several increasingly powerful drives from the pack paved the way for prop Bradley Ugodulunwa to score.
A couple of missed tackles helped Brighton’s impressive full-back Steve Morris to help himself to a fine solo try, taking the half time score to 19-17.
It didn’t look ideal for Wimbledon when they took to the field for the second half minus York and the equally influential lock Alex Campbell, but the reshaped pack continued their ascendancy over Brighton’s and soon earned a penalty which Moffat put over easily.
Then another excellent run by Brighton’s full-back was finally halted just short of Dons’ goal line, but a good ruck and a fine clearance by stand-off Steve Boatman – who had another good all-round game – and Dons were back in opposition territory.
From here the backs launched a slick attack, finished off by the forwards, with flanker Jack Flanagan claiming the bonus point try, Moffat converting.
Wing Alex Kane put Wimbledon out of sight with try number five after a lovely break from halfway. With 10 minutes remaining – and Wimbledon’s pack now dominant – they got a deserved penalty try to take the score to 41-17.
Brighton got a bonus point try, McIlwaine converting.
Wimbledon travel to fourth-placed Hertford on Saturday.