Rocastle has been on loan at Hibernian this campaign as well as spending a month at Oakwell last season and has been linked with a move to Wednesday for some time.
Obviously, Rocastle has had problems establishing himself in the reserve team at the Premiership leaders let alone the first team and the move to Hillsborough will be a welcome one for him.
He has signed a two-and-a-half year deal at S6 and is set to make his debut on Saturday against The Tykes.
Paul Sturrock has been chasing the player for quite a while and will be a ready-made replacement for Joey O'Brien who returns to Bolton shortly.