In the trade, the Broncos received Cravens and a fourth- and fifth-round draft pick this year (No's. 113 and 149).
In return, the Redskins received four draft picks -- a fourth-round pick (No. 109) and two fifth-round picks (No's. 142 and 163) this year, and a conditional selection in the 2020 draft.
"The move to trade Su'a is good for both organizations," Redskins senior vice president of player personnel Doug Williams said in a statement. "We wish him well."
The trade comes four weeks after Washington coach Jay Gruden told reporters that Cravens would not be traded.
Cravens was cleared to resume football activities in late December after suffering from post-concussion syndrome. He was reinstated by the NFL on Feb. 14.
A second-round draft pick in 2016, Cravens was placed on the exempt/left squad list on Sept. 3 after he said he wanted to retire. The 22-year-old Cravens reportedly was dealing with family issues at the time.
On Sept. 18, the Redskins placed him on the reserve/left squad list, which meant he was ineligible to play for the entire season.
In his 2016 rookie season, Cravens had 34 tackles, one interception and one sack in 11 games (three starts).