That arena was built in 1941 when the then prime minister of Thailand, Field Marshal Plaek Phibunsongkhram, gave orders to build a national boxing stadium on Rajadamnern Avenue. The first foundation stone was laid on March 1, 1941, but due to a lack of material supply during World War II, it was not until August 1945 that the arena was completed.

The original stadium was open-air, resembling a Roman amphitheatre in design. Six years later, in 1951 a concrete roof was added, making it weather-proof.

The arena is operated by Rajadamnern Co, Ltd. since 1953 after the government allowed Chalerm Cheosakul, the stadium manager at the time and founder of Rajadamnern Co, Ltd., to run the venue.

Along with Lumpinee Boxing Stadium, Rajadamnern is one of the two main stadiums for modern muay Thai. It hosts fights every Monday, Wednesday, Thursday and Sunday. The stadium has its own ranking system and championship titles up to middleweight (160 lbs).

As part of Rajadamnern World Series, on 22 July 2022, Rajadamnern Stadium hosted the first four female Muay Thai fights in its’ almost 8 decade-long history. 

According to Wikipedia.