The 27-year-old joins the Sounders after having spent the last five seasons with D.C. United.
“We are happy to have Marc signed,” said Sounders coach Sigi Schmid. “He will be a welcome addition to an already deep team.”
“I’m excited to take another step forward in my career and to play again for Sigi in Seattle,” Burch said.
“Seattle has made an impact during its short history since coming into league. I’ve always respected the way the Sounders played and I just want to help push them further.”
