Mrs Leadsom replaces Liz Truss, who now becomes Justice Secretary.
Andrea Leadsom is MP for south Northamptonshire and was formerly a Minister of State for Energy.
The appointment comes at a key time, as she will need to work out what the future of food and agriculture in Britain will look like following the vote to leave the EU. Issues that need to be addressed include trade agreements, labour availability, financial support, and legislation.
National Farmers Union (NFU) President Meurig Raymond said: “Following a period of uncertainty we are now entering a significant time for our nation following the Brexit vote and the NFU and farming industry is looking forward to working closely with Mrs Leadsom as we together help forge the future of farming and food production in this country.
“However, there are also many issues that need addressing more immediately - we need a simpler application process and improved delivery for BPS; we need a guarantee from Government that agreements for farmers in agri-environment schemes will be honoured in full; we need a continuing commitment to the 25-year TB eradication strategy.”
Mr Raymond added that he would like to see Mrs Leadsom champion British food and farming.
During Theresa May's cabinet reshuffle, she also merged the departments of Business and Energy and Climate Change, and created a new 'Brexit department'.
The remit for climate change will be contained within the new Department for Business, Energy and Industrial Strategy. Climate campaigners expressed concerns about the move.
Greenpeace Executive Director, John Sauven, said: “The energy and climate change change department has been broken up and put back together without the name 'climate change'. Although, some might say ‘what’s in a name’, there is a very real worry that the progress made on tackling climate change could be relegated to the bottom of the intray."
