The five-time Grammy Award winner had been a passenger in a car driven by her boyfriend when it was stopped near Sunset Strip for erratic driving.
Police arrested 25-year-old Matthew Rutler on suspicion of drink-driving.
Both he and Aguilera were taken to a West Hollywood police station.
Los Angeles Sheriff’s Department spokesman Steve Whitmore said the 30-year-old singer was “not capable of taking care of herself”.
“She was cooperative. She was not belligerent in any way whatsoever. She was just intoxicated.”
Aguilera was released after about four hours and will not be prosecuted.
Her boyfriend was released later after posting $5,000 bail.
Police say his blood-alcohol level was slightly above the legal limit.
