WBC Flyweight Champion

On March 2, 2001, Wonjongkam fought Malcolm Tuñacao for the WBC and Lineal Flyweight Championships.^[4] Tuñacao won the Flyweight Lineage Championship from Medgoen Singsurat, who won the title by knocking out Manny Pacquiao. Pacquiao would later become the number one pound for pound fighter in the world. Wonjongkam won by first-round TKO after knocking Tuñacao down three times.^[3]

In his fourth Lineal and WBC Flyweight title defense, on April 19, 2002, Wonjongkam knocked out Japanese flyweight titleholder Daisuke Naito in 34 seconds.^[3] This knockout set the record for fastest knockout in division history.^[5]

On November 17, 2006, Wonjongkam defeated South African boxer Monelisi Mhikiza Myekeni by unanimous decision.^[3] Wonjongkam set the flyweight division record for consecutive title defenses, 16, with this victory.^[6] He then successfully defended his title against Tomonobu Shimizu, after Shibizu retired on his stool between the 6th and 7th rounds. Shibizu was the 16th boxer Wonjonkgam defended his title against, establishing another flyweight record.^[2]

Wonjongkam was ranked number ten in Ring magazine's pound-for-pound rankings, but Jermain Taylor bumped him off the list on June 18, 2006. Wonjongkam was ranked as The Ring's number one flyweight^[7] until his loss to Daisuke Naito in 2007.

Losing the Title

Wonjongkam suffered a shocking upset decision loss to Daisuke Naito in July, 2007, ending his long run as champion. Wonjongkam had defeated Naito twice in previous titles defenses. On March 8, 2008, Wonjongkam faced Naito in a rematch which ended in a draw.

Wonjongkam vs. Miranda

Wonjongkam won the vacant Interim WBC Flyweight Championship in a bout against Mexican Julio César Miranda on April 24, 2009. The 12 round bout ended by a unanimous decision. Wonjongkam defended his interim title against Takahisa Masuda by knockout, setting the stage for a bout against Lineal WBC Flyweight Champion Koki Kameda, who had recently defeated Naito to win the title.

Recapturing the WBC Flyweight Championship

On March 27, 2010, Wonjongkam fought Lineal Champion, Koki Kameda, to unify the WBC Flyweight Championship and Interim WBC Flyweight Championship. The winner would also claim the vacant The Ring Flyweight Championship.^[8] Wonjongkam defeated Kameda by a 12-round majority decision to become the WBC and Ring Flyweight Champion.

Losing the WBC Flyweight Championship

On March 2, 2012, Wonjongkam lost his Lineal, The Ring and WBC Flyweight Titles in an upset technical knockout stoppage to Sonny Boy Jaro of Philippines. He was knocked down five times before the fight was stopped in the sixth round.

Later career

Wonjongkam won the vacant WBC International flyweight title against Hyobu Nakagama on August 31, 2012. However, he lost the title to Rey Megrino on November 1, 2012, by a third-round TKO, marking Wonjongkam's fifth defeat. Even more disappointingly for Wonjongkam, Megrino had a losing record of 17-20-3 going into this fight, and had been beaten twice before by Wonjongkam, first by ten-round UD in October 2007, and a first round stoppage in July 2010.