The winger, who left Wanderers at the end of last season, moves to Pittodrie until the end of the 2015 season.
And former Rangers man Wylde will be joined at his new club by teenage striker Lawrence Shankland, who has signed from Queens Park.
Aberdeen manager Derek McInnes said: "Gregg is a player will give us real pace and good balance, which is something I felt the team needed.
"He is a young player who has had a couple of frustrating years with injuries and not playing first team football but he is a player with great ability and is someone who I am sure will be hugely beneficial to the team."
Of Shankland, who scored 11 league goals for Queens Park last term, he said: "I'm delighted to have secured Lawrence. We feel he is an excellent acquisition.
"He will now gain the benefit of training full time and will play regularly at U20 level with a view to forcing his way in to the first team."