Jesse was born in Helsinki, Finland, on May 7, 1992. Since childhood, he loved to play football and has been involved in it for more than ten years.
He began his career in e-sports with such a discipline as Heroes Of Newerth, performed in different teams with such players as «Era» and «SingSing.» When the player reached draft army age, he completed compulsory military service in the Finnish Navy, and when his service ended, Jesse decided to return to eSports. But he chose to change discipline and began playing DotA 2.
Back in 2013, the player joined the Finnish team Rat in the dark as a support. After playing in this line-up for about a month, he accepted the offer of his old acquaintance «SingSing» and will join his QPAD Red Pandas team. «JerAx» agreed and successfully passed the trial period, after which he became a full member of the team. In 2014, he changed the vector of development and decided to move to a purely Swedish team, 4 Anchors + Sea Captain, with such a team as «Trixi», «MATUMBAMAN», «Vaalix» and «Buugi». He performed in 4 positions and was also a drafter and team captain. But in January 2015, he left the team. Jesse did not looking for a team for a long time because Team Tinker found him a few days after he left the old team. But after disappointing results, «JerAx» leaves Team Tinker and joins the Korean MVP HOT6ix team. The team literally immediately becomes one of the strongest in the Southeast Asian region. After winning the MPGL Season 7, the team goes to qualify for The International 2015. But this tournament was disastrous enough for the team. After that, Jesse returned to Europe and joined the new 5Jungz team. And already in the fall of 2015, they were signed by Team Liquid. The team had a reasonably successful season and became one of the strongest teams in the European Region. After winning the EPICENTER tournament in Moscow, the team was predicted to win prizes at The International. But something went wrong, and Team Liquid ate was able to take 7-8th place. After The International, Jesse decided to leave Team Liquid and decided to try himself at OG. In the new team, he became the two-time Major of Tournaments.
In the 2017-18 season, the team was on the verge of collapse, as two key players left it three months before The International 2018. However, «JerAx» did not withdraw the team at a difficult time. OG was not without difficulty at The International 2018 and sensationally won the tournament. In 2019, OG also wins at The International 2019. After which Jesse «JerAx» Vainikka becomes one of the few who won this tournament for two consecutive years. In September, the player took part in his last Dota 2 tournament, Midas Mode 2 - Europe, in which he finished fourth. After which, he announced that he was ending his professional career as a Dota 2 player.