The PM will visit Washington DC after Trump's inauguration, which is on 20 January, a senior Number 10 source told Sky News.
Trump invited May to visit him "as soon as possible" in a phone call the day after the US presidential election. Downing Street said May and Trump agreed the US-UK relationship "very important and very special" during the phone call, and that building on it in future will be a priority.
A Downing Street spokesperson said: "This was part of a process leading towards the PM's first visit with President-elect Trump. During the second phone call with President-elect Trump, the prime minister suggested it would be a good idea for key staff from both teams to meet. President-elect Trump agreed this would be useful.
"We are pleased to have been able to make that happen and the prime minister looks forward to visiting the new president in the spring."
Theresa May sent two of her most senior members of staff on a secret trip to the US to meet Trump's advisers after he declared former Ukip leader Nigel Farage should be the UK's ambassador to the US, the Telegraph reported today.
Farage was the first UK politician to meet with billionaire tycoon-turned-politician Trump, less than a week after his surprise victory against Democratic nominee and Washington veteran Hillary Clinton.