Broadcaster Eddie Mair will host the drivetime show on commercial station LBC - pitting him directly against his old PM show on BBC Radio 4.
The 52-year-old announced he will host a two-hour weekday programme, beginning at 16:00, from 3 September.
The veteran presenter, who left the BBC in August, previously hosted PM, which airs on Radio 4 from 17:00 to 18:00.
James Rea, LBC's managing editor, said it was "terrific to welcome Eddie to our powerhouse presenting team."
Iain Dale, LBC's current drivetime presenter, will host a new weekday evening show from 19:00 to 22:00.
Mair himself professed ignorance about the shake-up, tweeting: "Well this is the first I'm hearing of this."
Dale took the decision to give him a later slot in good part, calling Mair "one of the top five names in speech radio".
"When you get the chance to recruit someone like him you're a fool if you pass it up," he wrote on his personal blog.
"Eddie's signing makes our team stronger."
'A little different'
Mair made his last appearance on PM on 8 August, bringing to an end a 25-year association with the programme.
The show has had guest presenters since his departure and a full-time replacement is yet to be announced.
Writing in the Radio Times last month, Mair said he was leaving the BBC because he wanted "to do something a little different".
The Scottish presenter earned between £300,000 and £350,000 a year for his work on Radio 4's flagship news and current affairs programme.