According to a statement from her office, May and Saudi King Salman discussed "tax and privatisation standards to help Saudi Arabia diversify its economy and become less reliant on oil".
The UK will also assist Riyadh in "building a reformed Ministry of Defence" and reviewing defence capabilities, the statement said.
Saudi Arabia is faced with a significant budget deficit with billions of dollars in debts to private firms. The country is still reeling from a drop in global oil prices by about half since 2014.
As part of its economic diversification strategy, Saudi Arabia has announced plans to increase women's participation in the workforce from 22 to 28 percent by 2020.
Tuesday saw the British leader hold discussions with a number of Saudi officials, including Saudi Crown Prince and Interior Minister Mohammed bin Nayef and Defence Minister Mohammed bin Salman, who is second in line to the throne, as well as the country's oil and energy minister.
May also met Sarah al-Suhaimi, the first woman to head the Saudi stock exchange and a Saudi investment bank, and Princess Reema bint Bandar, head of the women's section at the General Authority for Sports.
London and Riyadh have long enjoyed close ties, with the oil-rich kingdom being the UK's leading economic partner in the Middle East.
This has brought the British government under fire for its controversial arms deals with Riyadh, particularly in light of the Saudi-led coalition's ongoing war in Yemen.
Saudi Arabia has purchased over $5 billion (4.7 billion euros) worth of arms from the United States and Britain since the beginning of its military intervention in March 2015, said the Stockholm International Peace Research Institute think tank.
Rights groups have called for an end to US and British arms sales to Riyadh over the coalition's alleged war crimes.
More than 7,700 people have been killed in Yemen since March 2015, the United Nations says, and seven million Yemenis face starvation this year.