Former International Development Secretary Priti Patel is likely to return to Cabinet as Boris Johnson looks to raise the numbers of women and ethnic minority ministers in his top team.
Mr Johnson is set to enter No 10 for the first time tomorrow.
But he has already begun work shaping what allies have described as a "Cabinet for modern Britain".
Ms Patel is expected to be joined at the top table by the Indian-born employment minister Alok Sharma.
Allies said Mr Johnson was looking to welcome a record number of ethnic minority ministers around the Cabinet table while also increasing the number a women attending Cabinet in their own right.
The first ministerial appointments are expected to be confirmed after Mr Johnson returns from Buckingham Palace following his audience with the Queen.
Among the lower ministerial ranks, he is looking to bring on rising talent in the party, with promotions expected for local government minister Rishi Sunak, Cabinet Office minister Oliver Dowden and Treasury minister Robert Jenrick.
There is also expected to be a return to government for Tracey Crouch, who quit last year as sports minister after clashing with the Treasury over delays to a crackdown on fixed-odds betting machines.
A source close to Mr Johnson said: "Boris will build a Cabinet showcasing all the talents within the party that truly reflect modern Britain."
Ms Patel's return comes almost two years after she was dramatically forced to resign after being summoned back from a visit to Africa by Mrs May over unauthorised contacts with Israeli officials.
Seen as being on the Thatcherite right of the Tory Party, she has long been a Brexit supporter.
In contrast, Mr Sharma campaigned for Remain in 2016, although he was among the early supporters to declare for Mr Johnson after Mrs May announced she would be standing down.