The 24-year-old had spent several weeks on trial with DCU as the club prepares for the 2017 MLS campaign.
"Max impressed us this preseason with his technical ability, intelligence and vision," United general manager Dave Kasper said in a club release. "He's a young, versatile player with solid MLS experience who adds depth to our defense and we¹re happy to welcome him to D.C."
Tissot most recently played in the NASL for the Ottawa Fury, and prior to that he was a member of the Impact for three and a half seasons. Utiized primarily on the left side in either defense or midfield, Tissot is expected to provide depth while also challenging for first team minutes in D.C.
Tissot has appeared 12 times for his country since debuting in January 2015.