Siwarak moved to BEC Tero Sasana FC in 2008. Although Siwarak played well in BEC Tero Sasana F.C. he was not always a starter, because Pisan Dorkmaikaew another goalkeeper in BEC Tero also played well. Therefore, the competition in the team is high, and being a starter is not guaranteed.
TOT
Siwarak moved to TOT S.C. in 2010, but didn't play any match for the team.
Buriram United
2010 Season
In 2010 Siwarak moved to Buriram PEA. He was Buriram United's best keeper and he became a regular starter for Buriram United.
Siwarak played in the 2013 AFC Champions League playoffs against Brisbane Roar FC, from his team's Thai FA Cup win. Siwarak's form in the 2013 AFC Champions League playoffs was extraordinary, after getting a clean sheet and saving three penalties in a row from players from Brisbane Roar FC. Buriram United qualified to 2013 AFC Champions League after winning Brisbane Roar FC in the penalty shootouts. After that Siwarak became number five of Asia in saving the most penalties. He played every game for Buriram United in the 2013 AFC Champions League. Siwarak also played every game for Buriram United in the 2013 Thai Premier League, he conceded 23 goals and got 13 clean sheets.
International career
Siwarak played for Thailand U-23 in the 2007 Southeast Asian Games, and won a gold medal. He played his 7th game for Thailand against Oman in the Asian World Cup Qualifying section in 2008, but after Thailand hired a new national team coach, he found himself left out of any squad call ups, missing out on the 2008 AFF Suzuki Cup. Siwarak was recalled to the national team for the 2009 King's Cup. In 2013 Siwarak played against Lebanon in the 2015 AFC Asian Cup qualification, after the first choice keeper Kawin Thamsatchanan got injured. In 2018 he was called up by Thailand national team for the 2018 AFF Suzuki Cup. Siwarak was named for the final squad in 2019 AFC Asian Cup, but initially only acted as third-choice behind regular Chatchai Budprom under Milovan Rajevac. However, after Chatchai's disastrous performance in the team's shocking 1–4 defeat to India, he was chosen as the team's custodian replacing Chatchai as Rajevac was fired. His performance in later matches against Bahrain, UAE and China earned him praises and reputations, in which he was accredited as an instrumental part for Thailand's return to the knockout stage since 1972. Siwarak was named captain by new coach Akira Nishino for 2022 FIFA World Cup qualification.
