The transfer fee for the 22-year-old United States men's national team defender was a reported $3 million. Cannon has earned 11 caps to date with the USMNT.
"I've always had aspirations to be one of the best full-backs in the world and I still have that dream," Cannon said in a statement. "I want to play in a World Cup one day, I want to make a name for myself.
"Dallas has provided me with that springboard and with that opportunity to ultimately go overseas and be challenged. I'm really excited for this opportunity and I thank [team manager] Luchi [Gonzalez], the club, the staff, and everyone that's given me an opportunity to get to the next level."
Cannon signed a four-year contract extension with Dallas last March.
He tallied one assist in five starts this season and has two goals and five assists in 67 games (64 starts) since making his MLS debut in 2017. He played one season at UCLA before signing with Dallas.
Earlier this season, Cannon received what FCD characterized as "racist comments and death threats" after taking a knee and raising his fist during the national anthem prior to a game against Nashville. MLS also condemned the messages.