Patel holds on to her position as the senior-most Indian-origin Cabinet minister and will remain in charge as the secretary of state for international development in the new government, which May said will focus on delivering a successful Brexit.
The Prime Minister said the new line-up brought in "talent from across the whole of the Conservative party".
"Crucially I've brought in talent from across the whole of the Conservative party. We want a country that works for everyone," she said in Downing Street.
May said she had appointed "a Cabinet that will get on with the job of government, which is about delivering successful Brexit negotiations. And those negotiations start in a week's time".
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The remaining Cabinet posts are set for a reshuffle from her previous administration, with today's key announcements.
Greg Clark holds on to his job as secretary of state for business, energy and industrial strategy and David Gauke takes over as work and pensions minister.
Liz Truss appointed chief secretary to the treasury, with right to attend Cabinet and Pakistani-origin Sajid Javid keeps hold of his post as secretary of state for communities and local government.
David Lidington takes charge as Lord Chancellor and justice minister and Alun Cairns as the new Secretary of State for Wales.
She has also kept Jeremy Hunt in his post as health secretary, Gavin Williamson is the new party Chief Whip or parliamentary secretary to the Treasury and Chris Grayling has been appointed transport minister.
The new Cabinet appointments will be seen as May's attempt at surrounding herself with as many allies as possible against the backdrop of a brewing rebellion within party ranks after the Conservatives suffered heavy losses in the June 8 general election.
Far from a forecast landslide majority, May has been left holding on to 10 Downing Street with diminished authority - having lost her party its majority.