Dennis-Lane arrives at St Kilda in exchange for pick 47, which the Saints secured as part of the deal that brought Tom Hickey to the club from Gold Coast.
After an impressive debut season in 2010 where he kicked 18 goals from eight matches, Dennis-Lane struggled with form and injury over the past two seasons, managing just 11 more games and another 12 goals.
Possibly his best game at the Swans was the 2010 elimination final when he booted four goals in the narrow win over Carlton at ANZ Stadium.
He was not part of the Swans' recent premiership win but at just 24, his best football could still be ahead of him.
Dennis-Lane joins Tom Lee as new recruits likely to add depth to St Kilda's forward line.
The Saints were active in the last day of the Gillette AFL Trade Period, securing a deal that sent Jamie Cripps and pick 46 to West Coast in exchange for picks 41 and 44.
But they failed to sign Mitch Brown after the Eagles refused to negotiate for the contracted defender.
Luke Holmesby covers St Kilda news for AFL Media. Follow him on Twitter - @AFL_Luke
