David Cameron will address the 1922 Committee of Conservative backbenchers on Monday, amid mounting fury over his appointment.
Cameron was appointed Foreign Secretary after James Cleverly was moved the Home Office to replace Suella Braverman.
The last time a former Prime Minister came back to the Cabinet was Alec Douglas Home, who returned to the Cabinet as Foreign Secretary in 1970.
The Foreign Secretary will address the 1922 Committee – the committee of all Conservative backbenchers – at their weekly meeting.
WATCH: David Cameron arrives at Downing Street
Concerns have been raised by MPs over his links with China, particularly since leaving office.
Luke de Pulford, the director of the Inter-Parliamentary Alliance on China, accused the former Prime Minister of “shilling for the UK’s biggest security threat”.
He hit out at the appointment, describing it as a “strategic own goal for Rishi Sunak”.
Meanwhile, at Prime Minister’s Questions on Wednesday, Labour leader Sir Keir Starmer urged Sunak to force Cameron to reveal his links with China.
Starmer asked: “When will he instruct the Foreign Secretary to give full public disclosure for his work for Chinese interests?”
Responding, Sunak said he was “delighted” Lord Cameron had returned to Government.
He said the former Prime Minister’s “unrivalled experience” will help the UK navigate an “uncertain world”.
Sunak added: “Like every other Government minister, he will go through the normal process with the independent adviser.”
The Prime Minister, who conducted a reshuffle of his Cabinet on Monday, said China presents an “epoch-defining challenge”, instead accusing the Labour Party of having “taken almost £700,000 from an alleged Chinese agent”.
Chinese state media welcomed Cameron’s appointment earlier this week.
In an Op-Ed published on Tuesday, state-run tabloid Global Times said the former PM could “play a constructive role, both in mending the UK’s relations with China and in rebuilding and advancing the UK’s post-Brexit diplomatic landscape”.
In a statement after his appointment, Cameron said: “I may have disagreed with some individual decisions” made by Rishi Sunak, but added that he “is a strong and capable Prime Minister, who is showing exemplary leadership at a difficult time”.
He said: “The Prime Minister has asked me to serve as his Foreign Secretary and I have gladly accepted.
“We are facing a daunting set of international challenges, including the war in Ukraine and the crisis in the Middle East.
“At this time of profound global change, it has rarely been more important for this country to stand by our allies, strengthen our partnerships and make sure our voice is heard.