He is a former six-time Lumpinee Stadium champion across four divisions as well as the 1998 and 2008 Sports Writers Association of Thailand Fighter of the Year.

Nicknamed the "Ultimate Boxer from Sarakham", he is often regarded as one of the greatest and most talented fighters in the history of Muay Thai.

His speed, athleticism, and the large variety in his unorthodox arsenal made him an exceptionally difficult opponent to prepare for.

[6] He retired from serious competition in Thailand in 2014 and now solely competes in showcase fights around the world against foreign, usually bigger opponents.

He decided to start learning Muay Thai in Jocky gym when his friend's elder brother received a prize after a bout.

On March 14, 2010, Saenchai fought against Tetsuya Yamato from Japan to challenge the vacant world lightweight title sanctioned by Muay Thai Association of America (MTAA) in Los Angeles.

[15] In the same year, Saenchai led the Muay Thai Combat Fan Expo[16] in Rimini, Italy with Buakaw Banchamek, Sudsakorn Sor Klinmee, Dzhabar Askerov and many others.

[17] He beat Pakorn Sakyothin by decision at Super Showdown 4 in Glasgow, Scotland on November 10, 2012,[18][19] and then took a points victory over Damian Alamos twelve days later at Best of Siam 2 in Paris, France.

[20][21] Saenchai then defeated Liam Harrison for the third time at Muay Thai Warriors in Macau on December 9, 2012, taking a clear-cut unanimous decision.

[31][32] He debuted under Oriental kickboxing rules[broken anchor] at Hoost Cup: Kings in Nagoya, Japan on June 16, 2013, and beat Yosuke Mizuochi by unanimous decision in a three-round fight.

[37][38] Saenchai ran through a field of overmatched farangs to win the Toyota Vigo Marathon Tournament on July 24, 2013, in Phitsanulok.

[41][42][43] It was reported that he would fight Mickaël Piscitello at the WBC World Muay Thai Millennium Championship in Saint-Pierre, Réunion on September 7, 2013.

[51][52][53] He was scheduled for a March 8, 2014, meeting with Irishman Stephen Hodgers at Origins IV at Welterweight (-64.00 kg/141 lb) in Perth, Western Australia.

Saenchai was unable to compete, however, as he did not meet certain criteria demanded by the Western Australia Combat Sports Commission and was replaced by Komkit Chanawong.

[55] Saenchai defeated Shota Sato via unanimous decision at Hoost Cup: Legend in Nagoya, Japan on March 23, 2014.

Saenchai Muaythaigym made his debut on the Thai Fight stage, defeating the strong Scotsman Craig Dickson (Sumalee) under Kard Chuek rules (with rope bindings taking the place of gloves).

[63][64] Saenchai fought and defeated American Arthur Sorsor by decision at KHMER - THAI FIGHT on November 25, 2017, in Phnom Penh, Cambodia.

[70] On October 27, 2018, Saenchai took a unanimous decision victory over Isaac Santos of Brazil at THAI FIGHT Chiang Rai 2018.

After three rounds, Saenchai was awarded the unanimous decision victory and was crowned the 2018 THAI FIGHT 67 kg King's Cup Champion, claiming his third consecutive promotional title.

[73] Saenchai began the year fighting at Yokkao 36 in Italy on January 26, 2019, where he defeated Cristian Faustino by unanimous decision.

[75] On March 8, 2019, Saenchai headed out for the UAE to compete at Fight Night Dubai to battle Valerii Abramenko of Ukraine, whom he defeated by unanimous decision.

At THAI FIGHT Mueang Khon 2019, he knocked out Javad Bigdeli of Iran in the 2nd round after a series of knees to the body.

On August 24, 2019, Saenchai defeated Cem Deniz of Australia by unanimous decision at THAI FIGHT Kham Chanod 2019 in Udon Thani.

In September, 2019, Saenchai went on a Muay Thai seminar tour in the US with Spencer Brown, Yodchai and Kru Jack.

[92] On August 2, 2022, it was announced that Saenchai had signed a multi-fight contract with Bare Knuckle Fighting Championship and is expected to debut in his native Thailand in late 2022.

[94] In mid-February 2023, it was announced that due to legal implications regarding the use of the name muay thai in marketing material, the bout was indefinitely postponed and effectively canceled.