ESPN's Adam Schefter first reported the deal.
Doctson, 26, spent his first three seasons in Washington after being taken in the first round of the 2016 draft. He was limited to two games due to an Achilles injury as a rookie and didn't ascend to stardom in either of the next two seasons.
Ben Standig of The Athletic reported Washington "lost faith" in Doctson and was looking to trade him before the beginning of the season. The team already declined its fifth-year option on the TCU product, making him a free agent next offseason.
Despite Washington giving up on him, Doctson still has fans in the locker room.
"He goes after the ball like no other. I'm talking about a jump ball," cornerback Josh Norman said, per John Keim of ESPN. "He has his strengths and abilities to where he can be one of the top guys in this league if he wants it. ... We have had a couple quarterback changes since he's been here. You have to take that into consideration."
The Vikings will be responsible for Doctson developing into a more consistent playmaker. At age 26 without much history of NFL success, it's unclear if Doctson will carve out a big role in Minnesota, but he could at least replace fellow 2016 first-round bust Laquon Treadwell, who was released last week.
Without much depth at receiver behind Adam Thielen and Stefon Diggs, he's worth a one-year contract to potentially provide the Vikings with another option in the passing attack.