A wealthy antiques dealer pleaded guilty Wednesday to strangling his 7-year-old daughter to death with a nightgown belt, according to reports.

In a surprise move, Robert Peters copped to murder charges as his trial at the Old Bailey in London entered its third day — the same day the girl’s mom, Krittiya Promsat, was set to testify against him, the Telegraph reported. 

Peters, 56, waited until Promsat had left their million-dollar home in Wimbledon Nov. 3 before waking Sophia up in bed and throttling her for as long as 30 minutes. He called police immediately, but the child, who was rushed to a hospital, died the next day. She suffered fatal brain damage.

“There’s been a murder,” he told police. He said a child had been killed and when asked who had done it, he answered, “I have.”

Following his arrest, Peters told a nurse that he twice tried to kill himself in 2017 and had considered for several weeks murdering his wife and daughter so they could be “spared the pain and upset when he became bankrupt.”

But in court, it was revealed that Peters was not in debt.

Earlier this year, the dad tried to plead guilty to manslaughter charges but denied murdering the girl, saying he was depressed and hearing voices at the time. The manslaughter plea was rejected — and his case went to trial this month.

Peters nodded as he admitted murdering Sophia. One relative who was in court repeatedly asked him, “Why?” as he was led out of the courtroom.

Judge Andrew Edis told jurors to return a guilty verdict.

“His guilty plea is the clearest evidence there could be of his guilt and in those circumstances the taking of a verdict from you is a necessary step, but it is a formal step,” he told the panel.

Peters, who ran an antiques business in Kensington, was remanded pending his sentencing Monday.