On her first bilateral trip outside Europe since taking office in July in the aftermath of Britain voting to exit the European Union, May will hold talks with her Indian counterpart Narendra Modi on Monday.
She will also inaugurate jointly with him the India-UK Tech Summit. Before leaving London, she described India as the UK's "most important and closest" friend and a leading power in the world, adding "We will be promoting the best of Britain, sending out the message that we are open for business, and making the most of the opportunities offered by Brexit as the world's foremost champion of free trade".
"I will be using this visit to reaffirm the importance of the strategic partnership we already have, which delivers huge benefits for both our countries, and to work with Prime Minister Modi to agree concrete steps to realise our shared vision of going even further in our cooperation across trade, investment, defence and security," she added.
May, who is accompanied by senior British ministers and a big trade delegation, will also travel to Bengluru on Tuesday where she will attend some business events and will meet the Karnataka Chief Minister.