After a Muay Thai career that saw him lose more fights than he won, Sithnaruepol turned to professional boxing in early 1982.
On March 24, 1988, Sithnaruepol fought Filipino contender Pretty Boy Lucas for the vacant IBF mini flyweight title at Rajadamnern Stadium in Bangkok.
In the 11th round, a facial injury left Lucas unable to continue, making Sithnaruepol the winner by TKO and Thailand's 11th world boxing champion.
Despite being a champion, Sithnaruepol was not as well known as contemporaries like Khaosai Galaxy, Sot Chitalada, or Samart Payakaroon, perhaps because the IBF was a newly formed organization and not well known in Thailand.
After retirement, he entered military service as a Sergeant Major Second Class (SM2) at Department of Army Transportation.