Former Love Island winner Jack Fincham was quizzed by cops shortly after 5am after they got a call claiming he was acting suspiciously.
Onlookers became concerned when they reportedly spotted him hanging around a car park in south east London in the early hours.
Four officers spoke to him before his family came to take him home.
Pictures show the reality star, wearing a blue and white jacket, looking bewildered as he is detained by police.
He had been spotted in the car park behind a row of semi-detached houses five miles from his family’s home in Kent.
One local in Bexleyheath said: “I have no idea why he was there.
“I only realised who it was after Googling.”
The incident last Sunday – 30 yards from a police station – came days before it was revealed that Fincham, 30, had split up from Towie girlfriend Frankie Sims, 26.
Jack’s representatives declined to comment. A source said: “I’m sure if Jack wishes to take to social media and explain the situation he will.”
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Nine days earlier he had been posting pictures of himself on holiday in Ibiza. On Friday he uploaded one in the sunshine with the caption: “Reflecting on things.”
The news of his split with Frankie came just hours after his ex Dani Dyer, 24, dumped her conman boyfriend Sammy Kimmence, who was jailed for swindling two pensioners.
A former stationery sales manager, Jack shot to fame in 2018 after he and Dani were crowned Love Island winners.
The pair split the £50,000 prize and carried on dating, moving in together and starring in their own spin-off.
But in 2019 Jack was forced to publicly apologise after it was revealed he had been on a cocaine binge. He admitted that he was “dreading” facing Dani’s dad Danny Dyer.
He became a dad with “great friend” Casey Ranger in January 2020.
Last November he was injured in a car smash outside a pub in Dartford, which saw his £35,000 Mercedes written off.
The Met said: “Police were called at 5.18am to reports of a man acting suspiciously. Officers attended and detained a man. No offences had been committed. He was collected by his family.”