The 30-year-old singer was picked up by a speed camera on the A40 Westway flyover as he broke the 30mph speed limit, going at 43mph.
Payne admitted the offence and apologised, court papers reveal, and he now faces a possible six-month road ban when he is sentenced next week.
The news comes after Payne had to cancel a South America tour on health grounds, and he was then reportedly taken to hospital in Italy with kidney pains.
The star, who was one fifth of One Direction before pursuing a solo career, was caught out speeding in his black Ford Ranger Wildtrak Deranged Edition just after midnight on February 24.
Writing to Lavender Hill magistrates court, Payne said: “I did not realise the speed limit and apologise for speeding.”
In an apparent reference to the court’s request for details of his finances, he added: “I am self employed and cannot provide the information at this stage. However I will pay any fine imposed within 14 days.”
Payne’s case has been dealt with through the Single Justice Procedure, allowing the court to handle it behind-closed-doors on written evidence alone.
According to court records, a court staffer adjourned the case last month until a hearing on October 9 “to consider disqualification from driving”.
Next week’s hearing is also expected to be behind-closed-doors, with Payne, who lives in Chalfont St Giles in Buckinghamshire, not due to appear in court.