Los Angeles County sheriff's Deputy Bill McSweeney says the 30-year-old accompanist was in a car apprenticed by her admirer that was chock-full on a West Hollywood artery at about 2:45 a.m. Tuesday.
Twenty-five-year-old Matthew Rutler was booked on suspicion of driving under the influence. He remains jailed on $30,000 bail.
McSweeney says Aguilera appeared extremely intoxicated and incapable of driving home, so she was taken to the West Hollywood sheriff's station and held until she sobered up.
McSweeney says Aguilera was released out a back gate around 7:30 a.m., avoiding paparazzi at the front.
Calls to her agent and publicist weren't returned early Tuesday.