Kristiansson played youth football in IFK Vaxholm, but never had a playing career, turning to management already at age 18, in 2001.[1] He coached youth teams in AIK, Hammarby IF and BK Forward before taking his first senior coaching position at Stene IF in 2006.[2]
In 2007 he was brought on as a football match analyst by Örebro SK, with whom he was affiliated for that year, and the Swedish Football Association, where he stayed longer.[2] Ahead of the 2010 FIFA World Cup, he was brought on as a match analyst for the Nigeria national football team under the Swedish manager Lars Lagerbäck.[1]
Returning to the Swedish Football Federation, in 2011 he got his first coaching position there, as assistant manager of Sweden U19 women[2] under Calle Barrling. They managed to win the 2012 UEFA Women's Under-19 Championship.[1] In 2013, Kristiansson moved on to AIK as assistant manager, before returning to the federation in 2016 as manager of Sweden U15–U17 women. From 2018 he managed Sweden U23 women as well as the Future Team, a "shadow" national team for mid-teen boys who are perceived to be talents, but less physically developed than the best players their age.[2] During this time with the federation, Kristiansson was also an analyst for Sweden's women's team at the 2016 Summer Olympics, the 2017 UEFA Women's Championship and the 2019 FIFA Women's World Cup.[1]
In 2021, Kristiansson once again went back to assistant manager for a men's Allsvenskan side, this time Örebro.[2] However, he left before the season was over, in order to take the reins at Hammarby TFF. Having helped them survive relegation from the 2021 Ettan, he was recruited for his first managerial position in the Damallsvenskan, at Vittsjö GIK.[3] He was co-manager with Tomas Mårtensson.[4]
In 2024, he moved back to Stockholm as U19 manager of IF Brommapojkarna.[5] Already after one year, the senior team needed a new manager following the departure of Olof Mellberg and Andreas Engelmark, and Kristiansson was chosen as co-manager with Fredrik Landén.[6][7] In their first year as managers, the team placed 12th of 16.[8]