Gordon was in New York City earlier in the day to meet with league officials, a source previously confirmed to ESPN.
Gordon, 26, has not played in a game since Dec. 21, 2014. He had been suspended indefinitely since September 2016 without pay for multiple violations of the NFL's substance abuse policy.
The league said that, effective immediately, Gordon may join the Browns to attend meetings and engage in conditioning work and individual workouts.
Subject to compliance with clinical and other requirements, he will be placed on the commissioner's exempt list and be permitted to practice with the team beginning Nov. 20.
Beginning Nov. 27, Gordon will be eligible -- at the team's discretion -- to return to active status or to remain on the commissioner's exempt list for an additional week before returning to active status.
If he abides by Goodell's stipulations, Gordon could play in Cleveland's final five games this season.
"We've been informed of the league's decision to reinstate Josh," Browns executive vice president Sashi Brown said. "The personal well-being of all our players is of the utmost importance to us. We respect and commend Josh for taking the steps necessary to have the opportunity to return to the league. Josh will be in our building in the coming days, and we look forward to having him back and sitting with him to discuss his future on our team."
Gordon has been in and out of rehab over the past year.
In the statement, NFL commissioner Goodell said Gordon's teammates and "all of us at the league office want him to have every opportunity to resume his career and to be successful in the NFL. Whether that happens, however, at the end of the day will depend on Josh. His commitment to sobriety and to reaching his goals in football and beyond will determine his success. It ultimately is up to Josh."
Information from The Associated Press was used in this report.