The visitors took a shock 53rd-minute lead through Nicky Adams but the effort was cancelled out just three minutes later when Frenchman Kermorgant smashed home his 25-yard set-piece.
Bradley Wright-Phillips was looking to end his goal drought stretching back to mid-November and went close twice early on, just failing to meet Bradley Pritchard's cross before drilling a low shot inches wide.
Wright-Phillips' 37th-minute header produced a save from Dale keeper Peter Kurucz and Matt Taylor headed wide three minutes before the break, but the two sides went in on level terms at the break after a lacklustre first half overall.
The game sprung into life early in the second period as lowly Rochdale grabbed a shock lead. Gary Jones broke clear down the right and his low cross was met by Adams, whose shot beat Ben Hamer with the aid of a slight deflection off Rhoys Wiggins.
But parity was restored soon after when Kermorgant fired a stunning free-kick beyond Kurucz for his first goal since Boxing Day.