Husband Jim Toth pleaded guilty to driving a motor vehicle with alcohol blood levels in excess of a legal limit, the celebrity news website said.
The 37-year-old actress, represented by lawyer Bruce Morris, entered her plea, in which she neither admitted nor disputed the charge of physical obstruction of another. She will pay a $213 fine, TMZ said.
Show business agent Toth was in court in person to plead guilty to driving under the influence and was sentenced to 40 hours of community service and was ordered to attend an alcohol education program, the website said.
He is on probation for 12 months.
"Consider yourself fortunate you didn't injure your passenger [Reese] and didn't kill anyone," TMZ quoted the judge as telling Toth.
Several hours earlier, Witherspoon told ABC's "Good Morning America" she was so alarmed when the police officer pulled her husband over that she said she was pregnant.
"I saw him arresting my husband and I literally panicked," she said. "I told him I was pregnant. I'm not pregnant. I said all kinds of crazy things."
Witherspoon and Toth were pulled over April 19 after police said the car he was driving weaved across a double line on Atlanta's Peachtree Street.
Toth, head of motion picture talent at Los Angeles' Creative Artists Agency, was found to have a blood alcohol level of 0.139 and was arrested and charged with DUI and failure to maintain a lane.
Witherspoon was arrested and charged with disorderly conduct after she disobeyed instructions from the arresting officer to remain in the vehicle and argued with him, allegedly saying she did not believe he was a real police officer and asking if he knew who she was.
"I was so disrespectful to him," Witherspoon told the program. "I have police officers in my family. I work with police officers every day. I know better. It's just unacceptable."
She said she and Toth had gone out to dinner and "had one too many glasses of wine."
"We thought we were fine to drive and we absolutely were not," she said. "We know better and we shouldn't have done that."
She said she and Toth "are so sorry and embarrassed" and said something like this "will absolutely never happen again."
The couple were married in March 2011 after a year of dating. They have a son, Tennessee James Toth. She has two other children -- daughter Ava, 13, and son Deacon, 9 -- from her marriage to actor Ryan Philippe.
The actress, now starring in the movie "Mud," is in Atlanta filming the drama "The Good Lie" with co-stars Corey Stoll and Sarah Baker.