Rich Cimini of ESPN.com reported the news.
Donahue, 25, has been arrested for driving under the influence twice in his NFL career. He faces drunk-driving charges stemming from a collision in May 2017 in Montana.
As part of the plea deal, Donahue will have his license suspended for three months and drive with an interlock device for a year thereafter. Donahue previously spent 30 days in a rehabilitation facility.
"It was very enlightening. I went through a lot," Donahue told reporters. "I volunteered to go down to inpatient treatment in Jacksonville. I think it was a life-changing experience. It was very awakening and life-changing this offseason."
The NFL will likely suspend Donahue under its personal conduct policy. Earlier this offseason, Arizona Cardinals general manager Steve Keim was suspended by the team for five games for his DUI conviction. The league suspended wide receiver Michael Floyd four games last year.
Donahue had five tackles last season.