McDonald, a free agent when the NFL league year begins in March, was originally charged with one misdemeanor count of driving under the influence of drugs. On Monday, McDonald pleaded guilty to what is commonly known as a "wet reckless."
McDonald, 25, was sentenced to three years of probation and was fined $390 plus penalties, the spokesman said. He also was ordered to complete a three-month alcohol program, 18 Narcotics Bnonymous classes and perform 200 hours of community service.
McDonald also was ordered to complete one month in a live-in residential drug program as well as make restitution to the victim in this case.
McDonald, who played at USC, said after the season that he would like to remain with the Rams.
"I don't know what the future holds for me here," he said, "but if the organization will have me back here I would love to be back."