49ers general manager John Lynch told reporters that Reed agreed to a one-year deal with the team. According to Lynch, the contract is heavy on incentives for the oft-injured Reed, who missed the entire 2019 season due to another concussion.
Reed, 30, suffered his seventh documented head injury -- since he began playing college football -- on a helmet-to-helmet hit in a preseason game last August. Once he finally cleared the NFL's concussion protocol earlier this year, Washington released him.
The 49ers spent time vetting the injury history of Reed -- who has never played a full NFL season due to various injuries -- and felt comfortable with signing him as they open training camp this week.
"In situations like this, there's a reason a guy like Jordan Reed is out there," Lynch said. "So there is some risk-reward. We got to a point where we felt like the risk that we're taking on was worth it with the potential reward."
Reed will be reunited with 49ers head coach Kyle Shanahan, who worked as Washington's offensive coordinator from 2010-13. Reed played one season under Shanahan after Washington selected him in the third round of the 2013 NFL Draft out of Florida.
In that season, Reed recorded 45 catches for 499 yards and three touchdowns in nine games before injuries forced him to sit out.
"I think everyone is aware of Jordan's ability," Shanahan said. "When he's been healthy, he's played at an extremely high level. He's been one of the best third-down tight ends in the league when healthy. ... I know he hasn't been on the field for a little bit. I know he's very hungry to get back out there. He hasn't got to do much of that lately."
In 65 career games, Reed -- a Pro Bowl selection in 2016 -- has tallied 329 catches for 3,371 yards and 24 touchdowns.
Reed will join All-Pro George Kittle, Ross Dwelley and rookie Charlie Woerner in the 49ers' tight end room.