Lenoir was a second-team All-Pac-12 selection in 2019 and has started 27 consecutive games. The 5-foot-11, 203-pound senior has recorded 124 tackles, five interceptions, 26 passes defended, a forced fumble and a fumble recovery during his Oregon career.
He tweeted "UNFINISHED BUSINESS 'Im Not Leaving' #GoDucks," on Monday.
The Ducks also added former Boise State safety Jordan Happle, who announced Monday he has joined the team as a graduate transfer. In 26 career games for the Broncos, Happle finished with 61 tackles, an interception and four passes defended.
No. 12 Oregon is widely considered the Pac-12 favorite, but it will also be without Outland Trophy winner LT Penei Sewell, Mel Kiper Jr.'s No. 2-ranked NFL prospect, who also opted out of the season to focus on the draft.
The Ducks begin a seven-game Pac-12 season Nov. 7 at Stanford.