Rice was arrested in February and charged with simple assault-domestic violence after an incident involving then-fiancee Janay Palmer at a casino in Atlantic City.
Surveillance video posted online by TMZ.com showed Rice lifting a motionless Palmer out of an elevator and onto a hallway floor.
Although there was no video of any physical altercation between the two, a grand jury indicted him in March on a charge of aggravated assault, meaning the jurors believed there was enough evidence for the case to go to trial.
In May, Rice was accepted into a pre-trial intervention program that allowed him to avert prosecution and avoid serving any time in jail.
The charges against him will be expunged from his record upon successful completion of the one-year program, and Rice and Palmer have since been married.
Nevertheless, the league said Thursday that the three-time Pro-Bowler had violated its personal conduct policy. He will miss the first two games of the season and be docked three games' pay.
In a letter to Rice released by the league, NFL Commissioner Roger Goodell says he believes Rice is sincere in his desire to move on from the incident, but said the league had to act.
"The league is an entity that depends on integrity and in the confidence of the public and we simply cannot tolerate conduct that endangers others or reflects negatively on our game. This is particularly true with respect to domestic violence and other forms of violence against women," Goodell wrote.