The 49ers traded with Washington to get the 44th overall pick.
San Francisco used the choice on Washington receiver Dante Pettis, a slot receiver and punt returner.
Pettis made 163 catches for 2,256 yards and 24 touchdowns in his four-year career, including 63 catches for 761 yards and seven touchdowns last season. He earned first-team All-PAC 12 honors.
Pettis set the NCAA record with nine career touchdown returns. He averaged 13.7 yards per punt return.