The 42-year-old TV presenter was ferried home in a Mercedes people carrier after spending hours in custody.
He was involved in a crash with two other cars while driving his Mini in Richmond, west London on Sunday, and was arrested at around 4pm.
A three-year-old girl was taken to hospital as a precaution following the crash.
It was reported that McPartlin lost control of his car at a roundabout before hitting another vehicle.
The troubled I'm A Celebrity presenter was taken to hospital before being released in the early hours of this morning.
He returned to his home in Chiswick at about 2.40am after spending about 10 hours in police custody.
McPartlin’s mother Christine Woodhall left the star’s £2m home in a black Mercedes people carrier at 11.35am today.
Earlier a woman, believed to be his PA, entered the detached Chiswick property.
McPartlin was driving with his mum in his Mini when he reportedly hit two cars. A green Mini carrying a family was left badly damaged after the crash in Lower Richmond Road.
Amy Cassie, 23, who said she helped Ant's mum get the dog out of the car, told the Mirror: “Ant seemed furious after crashing the car and was shouting at his mum who was also in the car. She was trying to get him to calm down.
“The police took him to the back of the police car to remove him from the situation."
A Metropolitan Police spokesman said that a 42-year-old man was "taken to a south London police station for questioning and has since been released under investigation."
Inquiries continue, the spokesman added.
Police previously confirmed that a number of individuals were treated at the scene for minor injuries, and a child passenger from one of the cars was taken to hospital to be checked as a precaution.
This is the latest in a string of personal setbacks for the star, one of Britain's most well-known TV personalities, who works alongside co-star Declan Donnelly.
McPartlin entered rehab last year after struggling with an addiction to painkillers following a knee operation in 2015.
He returned to screens in November for I'm A Celebrity ... Get Me Out Of Here! and jokingly mentioned his rehab stint along with his TV partner.
In January, McPartlin confirmed that he and his wife Lisa were separating after 11 years of marriage.
At the National Television Awards a few days after the split, McPartlin referred to his "tough year" while picking up the presenting prize with Donnelly.