Trevelyan, who was appointed transport secretary by former prime minister Liz Truss, will now serve as a minister for the FCDO.
She said via Twitter: "Honoured to be asked by the prime minister to serve in the [FCDO] as one of his ministers. I am excited to have the opportunity to continue to champion our UK values and partnerships with friends and allies across the globe."
The new prime minister also removed Kevin Foster as transport minister, who will continue as a backbencher and MP for Torbay.
He said: "Just spoken with Rishi Sunak and sorry to be leaving government, but will be busy representing Torbay from the backbenches in the House of Commons tomorrow."
He will be replaced by former FCDO minister and MP for Hereford and South Herefordshire Jesse Norman – a vocal supporter of Sunak’s bid to become the country’s new leader.
