The versatile defender joins the Columbus Crew after a year spent with the Montreal Impact and Colorado Rapids.
"Tyson's signing gives us depth and experience at multiple defensive positions," Crew technical director Brian Bliss said in a team statement. "As a naturally left-footed player, he can play left back and center back, which are two areas where we're in need of versatility."
Wahl, who will be entering his eighth MLS season, spent last year split between the Montreal Impact and Colorado Rapids. He was acquired by the Impact from the Seattle Sounders in exchange for allocation money prior to Montreal's expansion season and started 11 games for the Canadian side. He was dealt to Colorado in exchange for a 2014 international roster slot in July and went on to play in four games for the Rapids.
Wahl was a free agent after going unselected in the December Re-Entry Draft. In addition to his time with the Rapids, Impact and Sounders, Wahl also played three years for the Kansas City Wizards (now Sporting Kansas City), where Bliss was formerly a coach.
"Tyson has a history in the league," Bliss said. "I have a history with him from Kansas City, so we know what he can do. He'll be a valuable asset to our team."