The yellow bus, which has two large photos of the prince on the side, was seen driving through Mayfair on Friday.
It came after US federal investigators accused the Duke of York of providing “zero cooperation” in their investigation into convicted sex offender Jeffrey Epstein and his co-conspirators.
The FBI has been attempting to talk to Prince Andrew about his friendship with Epstein, who died in his jail cell last year.
A banner on the side of the bus said: “If you see this man please ask him to call the FBI to answer their questions.”
The banner also featured a URL address for the website of Gloria Allred, a US attorney who is representing several of Epstein’s accusers.
During a press conference in New York last year, she said Prince Andrew had an obligation to meet with investigators to disclose what he knew about Epstein’s behaviour.
The Independent has approached Ms Allred to confirm if she commissioned the bus.
Prince Andrew has been embroiled for months in controversy over allegations that he slept with Virginia Giuffre - a woman who claims she was trafficked by Epstein when she was a teenager.
The Duke has repeatedly denied all allegations levelled against him.
He stepped down from public life in November after a disastrous Newsnight interview addressing the allegations against him.
The prince was widely mocked for his answers to questions about his conduct and accused of lacking empathy towards Epstein’s victims and failing to show sufficient regret for his friendship with the convicted sex offender.
When asked about his relationship with Epstein, the Duke said: “The people I met and the opportunities that I was given to learn either by [Epstein] or because of him were actually very useful.”
He added: “Do I regret the fact that he has quite obviously conducted himself in a manner unbecoming? Yes.”
Additional reporting by SWNS