He is good friends with former UFC veteran and Norwegian Brazilian jiu-jitsu specialist John Olav Einemo.

[1] His performance got him invited to Shooto's year-end show in 2002 where he, with a 3–1 record, faced Takumi Nakayama who at the time had 14 fights under his belt.

The fight went the distance with Hansen being awarded a majority decision, making him the Shooto Lightweight Champion and first Scandinavian person to hold a MMA world title.

[6] Hansen went on to win his next seven fights, most notably against Gesias Calvancanti, Caol Uno, Masakazu Imanari and Yves Edwards, before losing a decision to Hayato Sakurai in the semi-finals of the Pride 2005 Lightweight tournament.

Hansen then went 2–2 in his next four fights, losing to Shinya Aoki and Eiji Mitsuoka, before his next big win against Kazuyuki Miyata at K-1 Premium 2007 Dynamite!!.

[9] After a close fight Alvarez was awarded a unanimous decision and advanced to the Dream 5: Lightweight Grand Prix 2008 Final Round.

This became Hansen's ticket to the final after Alvarez, who went on to defeat Tatsuya Kawajiri in the semi-final, but was forced to withdraw due to a cut under his right eye.

[12] After the bout Hansen told the crowd he wanted his first title defense to be against Eddie Alvarez whom he replaced, and who had previously eliminated him from the tournament.

2008 on 31 December 2008, but the bout was canceled the day of the event due to Hansen not passing pre-fight medicals and subsequently being hospitalized for a "head injury".

[22][23][24] In his sophomore apprearence as a shootboxer, Hansen gained his first win as he took a unanimous decision victory over Kenji Kanai at Shoot Boxing 2013 - Act 1 in Tokyo on 22 February 2013.

In a Facebook message from his then manager Aron Jahnsen, Hansen suffered a stroke and despite later being offered a fight for a European organization, he reportedly turned it down.