BBC deputy political editor John Pienaar is leaving the broadcaster to join Times Radio.
Pienaar, 63, said he was quitting after nearly three decades at the BBC.
His announcement follows reports that Times Radio, a News UK station, is making big-money offers to hire BBC stars.
Pienaar tweeted: “Personal news: After nearly three decades at the BBC I am leaving to join the soon-to-be-launched Times Radio as Drive Time presenter.
“It’s been an enormous privilege and pleasure to report and present for the Beeb, and I’ll miss having many of the best people on the planet as colleagues.”
He added: “Now, I’m beyond excited to be part of the newest digital venture under the oldest and greatest title in journalism. More details of that to come.”
Pienaar is also known for Pienaar’s Politics on BBC Radio 5 Live.
His announcement comes as the BBC is under pressure from the Government.
Downing Street is reportedly considering replacing the TV licence fee with a subscription model, forcing the sale of most BBC radio stations, cutting the number of television stations and reducing the amount of online content.
However, Conservative MP Huw Merriman warned his own party against “picking a potentially unpopular fight” with the BBC.
He warned, in a column in The Daily Telegraph, that the corporation “should not be a target”.
The BBC’s accounts for 2018/19 said Pienaar earns between £160,000 and £164,999.
The Guardian reported on Saturday that Times Radio is making lucrative offers to hire leading BBC presenters.