The NFL announced Friday that Foster will be fined two game checks and not suspended.
"Following a thorough investigation, the evidence did not support a finding that Foster violated the NFL's Personal Conduct Policy in connection with the Tampa incident in November 2018," the league said in a statement. "The NFL has returned Foster to the active roster from the Commissioner Exempt list. He may fully participate in all team activities."
Foster has accepted the league's disciplinary measures and will not appeal the fine, NFL Network's Tom Pelissero reported.
"I am grateful to the Washington Redskins and the NFL for giving me this second chance," Foster said in a statement though the team. "I appreciate the support I have received from the league, my team, and my union to help me succeed. I want to thank Commissioner [Roger] Goodell for the time that he has spent with me and for his understanding of me as a person.
"I accept the NFL's decision and want to say that I am truly sorry for my past actions and the people who may have been hurt by them. Going forward, I will follow the plan outlined for me and work hard to earn back the trust of my teammates, the NFL, NFL fans, and the community. I know that my success is all up to me, and I am committed to not letting you down."
Foster's November arrest in Tampa, Fla., over allegations of domestic assault resulted in his release by the San Francisco 49ers. The Redskins claimed Foster three days later, but the league placed the linebacker on the Commissioner's Exempt List, which prevented him from playing and practicing until the NFL's investigation ran its course.
Florida prosecutors later dismissed a misdemeanor domestic violence battery charge against Foster on Jan. 3.
"Foster has acknowledged that he is responsible for his actions, and he has committed to a comprehensive accountability plan developed by the league, the NFLPA, and the Washington Redskins to help him grow personally and avoid future misconduct," the league said in a statement. "Foster was advised that any future incidents will likely result in more substantial discipline."
Since entering the league as a first-round pick with San Francisco in 2017, Foster has endured multiple run-ins with the law. He faced a charge of second-degree marijuana possession in Jan. 2018 in Alabama before the charge was dismissed when Foster completed a first-time offender diversion course.
Foster then faced charges of domestic violence, making criminal threats and weapons possession in California in Feb. 2018 before a judge dismissed the domestic violence charges.