The 27-year-old, who was a free agent after being released by the Seagulls during the summer, has signed an initial five-month deal at Spotland.
Dicker has admitted that he is looking forward to playing for the League Two club.
"The move came about pretty quickly and I'm looking forward to getting back out on the pitch," he told Rochdale's official website.
"Because you haven't signed for a club straight away people think you are holding out for this or that but it wasn't the case. I spoke to a few clubs but for whatever reason things didn't work out.
"I spoke to [manager] Keith Hill and thought about the move for a bit. I spoke to a few players who have played under him and they all think highly of him so I think it'll be a good move for both of us"
Dicker made 153 appearances for Brighton during four years with the club.