Thitikul was born on 20 February 2003 in Ratchaburi to Montree Thitikul and Siriwan. She first started playing golf at the age of 6 years old. She is popularly known by her nickname "Jeen", or "Jeeno Jat".
2017 season
Her emergence onto the international golf scene came with her victory at Ladies European Thailand Championship on the Ladies European Tour. She had already appeared, 3 days after her 14th birthday, in the Honda LPGA Thailand on the LPGA Tour, where she finished 37th out of the 66 competitors. She had earned her place in the field when she finished runner up in the Thailand Amateur Open the previous August, when she was just 13 years and 6 months old. After competing in the LPGA event, she won the Taiwan Amateur Open that was held three weeks prior to the Ladies European Thailand Championship at the Phoenix Gold Golf and Country Club. Her amateur status meant that she could not claim the 1st prize of 45,000 euros for winning the Ladies European Thailand Championship but it did get her an entry into both the Women's British Open and The Evian Championship in France. She missed the cut at the British Open by a shot but made the cut at the Evian Championship, playing the final two rounds and finishing in 64th place. Thitikul also competed at the Junior Dutch Open in July. In the final round she carded a course record 8-under-par round to win the tournament by eight clear shots. In August 2017 at the Southeast Asian Games in Malaysia, she won both the individual gold medal and was part of the Thailand team that won the gold event.
In February 2018, she competed in the Women's Amateur Asia-Pacific Championship in Singapore, just as she turned 15. She was part of a four-way tie in the final round but went onto to win the title. Her victory earned her a place in the HSBC Women's Champions on the same course, plus entries into the ANA Inspiration at Mission Hills, California and for a place in the British Open, for a second year running. At the HSBC event, she finished in eighth place. At the ANA Inspiration in March 2018 she finished in a tie for 30th place. At the British Open, she was the low amateur, and the only one to make the cut. At the 2018 Summer Youth Olympics, Thitikul teamed with Vanchai Luangnitikul to win the mixed team gold medal.
2017 Taiwan Amateur Championship, Dutch International Junior Open, Southeast Asian Games – Gold Medal, Santi Cup, Pondok Indah International Junior Championship
