He spent his early education at schools in Thailand before attending private secondary schools in the United Kingdom and Australia including King's Mead School, Seaford and Millfield School, Somerset and The King's School, Sydney. He then attended the Royal Military College in Australia. He also completed an arts degree at Sukhothai Thammatirat University in Bangkok.
He was created the Crown Prince of Thailand after he turned 20 years old in 1972.
He later graduated from the Royal Military College, Duntroon in Canberra, Australia. An officer in the Thai military, he trained with the Australian, British and United States armed services. He is a qualified military pilot and helicopter pilot. He took an active part in military operations against the Communist Party of Thailand during the 1970s, and also led combat operations against a Vietnamese military incursion across the border from Cambodia. Since 1975, he has served as a career officer in the Royal Thai Army. He served as a staff officer in the Directorate of Army Intelligence, and in 1978 he became head of the King's Own Bodyguard Battalion. In that year, however, he interrupted his military career to be ordained for a season as a Buddhist monk, as is customary for all Thai Buddhist males.
On 3 January 1977 Vajiralongkorn married Princess Soamsavali Kitiyakara (born 1957), a first cousin on his mother's side. They had one daughter:
- Princess Bajrakitiyabha ( 1978).
They were divorced in 1993 after being separated for several years. He married Mom Sujarinee Mahidol na Ayudhaya in February 1994. Together, they have three sons and one daughter:
- HRH Prince Juthavachara Mahidol (1979)
- HSH Prince Vacharaesorn Mahidol ( 1981)
- HSH Prince Chakriwat Mahidol (1983)
- HSH Prince Vacharaesorn Mahidol (1985)
- HRH Princess Sirivannavari Nariratana (1987)
She fled to England with the children in 1996, after a fight with her husband. He accused her of committing adultery with a 60 year old air marshall. The prince abducted their daughter and brought her back to Thailand to live with him. Their daughter was later elevated to the rank of Princess whilst Sucharini and her sons were stripped of their diplomatic passports. She and her sons later moved to the United States. As of 2007, Sujarinee is known as Sujarinee Vivacharawongse. The Prince married a third time in 2001, to Srirasmi Akharaphongpreecha. Together, they have one son:
- HRH Prince Dipangkorn Rasmijoti (2007)