The Prime Minister has been seeking an adviser to give on-the-record White House-style briefings to the press to take place on camera.
Downing Street did not comment, but a source told the PA news agency that Stratton will be appointed to the role.
Stratton has a rich history in broadcast journalism, having been national editor of ITV News, political editor on BBC Newsnight and co-presenter of ITV’s Peston On Sunday.
In July, Number 10 began the search for someone to “communicate with the nation on behalf of the Prime Minister”.
As opposed to an impartial civil servant, the politically-appointed special adviser will be able to take aim at opponents and defend the Government’s actions.
And unlike other influential figures in Downing Street, such as Johnson’s chief aide Dominic Cummings and communications director Lee Cain, the spokesperson will operate in the public eye.
Stratton, whose newspaper roles have included political correspondent at The Guardian, only left ITV to join the Chancellor’s team in April.
But she has long been a favourite for the new role with Number 10, with Downing Street having been impressed by her abilities.
The job advert said the salary would be “based on experience” but there have been suggestions the taxpayer-funded role could pay £100,000 a year.
Ministers are expected to appear alongside her at times.
The political reporters based in Parliament – known as the Lobby – currently have twice daily briefings with the Prime Minister’s official spokesman, or his deputy. They are both civil servants.
The briefings are on the record, so journalists can quote them, but they are not broadcast.
However, under proposals set out earlier this year, Stratton will face the cameras at 9 Downing Street during afternoon sessions.
In response to the move from Number 10, Labour leader Sir Keir Starmer began plans for monthly press conferences.