Ser-od began his international career in 2002 and has competed in the marathon at ten consecutive editions of the World Championships in Athletics since 2003.

[7] He remained in East Asia in 2007, coming 55th at the 2007 World Championships in Osaka before making another large improvement at the Beijing Marathon, where he completed the distance in a time of 2:16:22 hours.

[8] At the Good Luck Beijing Marathon, a test event for the 2008 Summer Olympics, he cut two more minutes off his best to defeat all opposition and win the race in a Mongolian record time of 2:14:15 hours.

[3] His final race of the year came at December's Hofu Yomiuri Marathon, but his fast starting pace saw him drift back into sixth by the finish.

[10] His training in Mongolia was interrupted by the cold winter and, in April 2009, he travelled to Gateshead, United Kingdom to visit family.

[1][2] Ser-Od trained on a running track for the first time at the Gateshead International Stadium and said that the area's 10 km competitions were of particular benefit, given the rarity of races over that distance in East Asia.

[1] He won 10K races in North Shields, Newton Aycliffe and Morpeth, as well as placing top three in half marathons in Redcar and Mansfield.

[13] The change of location resulted in a rise in the rankings in the World Championships Marathon in Berlin, as he finished in the top thirty for the first time, completing the course in 2:17:22 hours.

[17] In his fifth outing over the distance that year, he won the Hofu Yomiuri Marathon, succeeding on his third attempt in a time of 2:14:49 (the third best performance of his career).

[3][18] Ser-od's 2011 season started at the Northern 12-Stage Road Relay, where he led off the Morpeth Harriers team which went on to take the title.

[22] In 2011 Hofu Yomiuri Marathon in Japan he defended his title as winner running for 2:11:56 hours improving his time by 2 minutes and 53 seconds than the previous year.

Just months later, Ser-Od built on his Asian Games success with his personal-best and national-record time of 2:08:50, at the Fukuoka Marathon in December 2014.

[34] Ser-Od Bat-Ochir competed in the men's marathon at the 2020 Tokyo Olympic Games in August 2021, where he did not finish, after battling an illness.