The victory was made even sweeter by the 29-year-old's goal in the season-finale match in front of 63,854 Yakohama Marinos fans packing Nissan Stadium in Yokohama on Saturday (Dec 7).
"I am glad to have come this far," the Thai defender said in a post-game press conference after the team disposed of past title rivals FC Tokyo 3-0 to clinch their first J-League trophy since 2004.
"I would like to thank all Thai fans, Yokohama fans and the support from SCG Muang Thong United that made this possible," the 29-year-old added.
The result made him the first player from Thailand to capture the J-League trophy.
Theerathon played a part in the win by scoring the first goal 26 minutes into the game, although he admitted that Lady Luck was on his side.
Yokohama, led by former Australia head coach Ange Postecoglou, dominated from the start and took a 2-0 lead into halftime courtesy of Theeratorn Bunmathan’s deflected effort and Brazilian forward Erik’s neat finish.
Despite having goalkeeper Park Il-Gyu sent off midway through the second half, Yokohama wrapped up the win courtesy of substitute Keita Endo’s counter-attack goal with 13 minutes remaining.
Theerathon’s speculative effort took a heavy deflection off FC Tokyo captain Keigo Higashi and looped over the goalkeeper, leaving the crowd at the stadium dreaming of a first title in 15 years.
"I tried for a goal and it was lucky," he said.
Erik’s goal shortly before halftime all but secured the title and left Tokyo an almost impossible task of having to score six goals in a half to get their hands on the trophy.
“We played fantastic football. The players deserve this as they have played fantastic football all year,” said Postecoglou.
“Very proud of the players, the staff and we have fantastic supporters so I am very happy for everyone.”
Second-placed Tokyo came into the match needing to win by four goals to bring a first J-League title back to the capital, but that never looked likely as Postecoglou’s side attacked with the fervour and precision that has served them so well this season.
Yokohama have scored more goals than anyone else this season and posses the league’s top goalscorer in Brazilian Marcos Junior.
Park’s sending off for a rash challenge on Tokyo striker Kensuke Nagai with 30 minutes remaining would have made only the most pessimistic of Yokohama fans worry, but Endo’s goal on 77 minutes put all fears to rest.
Yokohama finish the season on 70 points, six clear of Tokyo in second.