The former transport secretary was a firm supporter of Rishi Sunak during the Conservative Party leadership election in the summer and had briefly stood for the role himself.
According to the BBC, Shapps said it was a "great honour" to be home secretary and praised the work of chancellor Jeremy Hunt.
He reportedly said it had been a "turbulent time for the government", but added he was "looking forward to getting stuck into the role… regardless of what is happening in Westminster".
