Howard, who has also had spells at Arsenal and Falkirk in his career, has been tracked by the Dons since the end of last season. He spent most of last term on the bench, only playing the last two games, and his move to Pittodrie will only see him become number two to Jamie Langfield. In effect, he faces a similar fight to the one he had at Saints - but will probably be on more money.
Dons boss Mark McGhee today said: "We have signed Mark on a one-year deal.
"Now the challenge for Mark is to put pressure on Jamie Langfield for that number one jersey."
Howard signed for Saints three years ago to provide competition to Chris Smith and played a few games in 2007/08 before playing most of the following season.
Howard follows Smith out the exit door in the last week and while that frees up a large chunk of wages, it also leaves us with just Gallacher and goalkeeping coach Paul Mathers. Another keeper needs brought in and there are rumours Ludovic Roy - who won the first division with Saints a decade ago - is in training with the squad, as is former Ayr and Kilmarnock goalie Craig Samson. The best performer could get a deal.
In other former keeper news, Jake Cunningham - who was released last month - is on trial with Blyth Spartans.
Story source: The Aberdeen Evening Express