The Brighton defender's attempted block of Tammy Abraham's shot diverted the ball into the net for the Swans' consolation at the Amex Stadium.
It meant that Dunk equalled Martin Skrtel's Premier League record of four own goals in a season, set in 2013/14.
In Skrtel's defence, the centre-back contributed seven goals in the right net for Liverpool that season.
All of Dunk's own goals have come via deflections of crosses or shots.
His first came on the opening weekend, against Manchester City, when he diverted Fernandinho's cross into his own net.
A week later he deflected in Philippe Coutinho's shot at home to Liverpool.
Skrtel is next with seven.
Of course, as far as Dunk is concerned, what cannot be measured is how many opposition goals have been prevented by his willingness to put himself in the way.
He is the clear leader for blocks in the top flight this season and no doubt will continue to place his body on the line to thwart opponents for the benefit of his team's battle to stay up.