Prasert Prasarttong-Osoth was born in Bangkok in 1933. Coming from a family that made a living from making and selling traditional Thai medicines, it was no surprise when he attended Mahidol University at their Faculty of Medicine in Siriraj Hospital. On receiving his bachelor's degree he qualified as a doctor, becoming a surgeon.

In 1972 he co-founded Bangkok Dusit Medical Services, which has become the largest private health care group and hospital operator in Thailand. He is currently the president and CEO of the group. Part of their portfolio includes a luxury healthcare facility in Bangkok complete with a Movenpick hotel.

Prasert owns Bangkok Airways, where he is also CEO and vice chairman. He lives with his wife and family in Bangkok.