The 27-year old has signed a one-year deal with the New Zealand club and joins after making 35 appearances and scoring five goals with the Mariners.
Phoenix chief Tony Pignata was delighted to welcome Macallister to the club, saying he would be a great asset.
"We have been looking for a targetman and Dylan will really fit that bill," said Pignata. "He's young but very experienced and has the quality and pedigree we've been looking for.
"It's fair to say he probably didn't have the season he wanted in 2009/10 but we're confident he'll come here to Wellington and turn things around. He's got the ability and he's the sort of player that will fit in well with the team and the team balance and that'll allow him to play the sort of football we know he's capable of."