He is currently fighting out of Rumble Sports, Copenhagen, Denmark, while representing Kaisho Martial Arts, Helsingborg, Sweden in grappling.

Nilsson started practicing judo at age of fifteen and this became a natural gateway to his interest for other martial arts.

The following years resulted in many trips to the podium including a first place in the Danish Brazilian jiu-jitsu open where he competed in the 205 lbs division.

Prior to the Fighter Extreme 2 championship many of Nilssons training partners practiced submission wrestling.

Three years after the initial success in Copenhagen, Nilsson took third place at ADCC- Germany in the 190 lbs weight class.

He competed in the -90 kg weight class and after four wins, of which three was submission victories, he took home the gold medal.

After losing the final with the closest margin possible Nilsson finished second after a loss against Alexander Bergman in the -91 kg division.

[8] On 29 September 2011, Nilsson once again competed in the FILA Grappling World Championship this time held in Belgrade, Serbia.

[3] On the 28 of July 2012 Nilsson won his third bronze at the FILA Grappling European Championship that took place in Brussels, Belgium, now in the -92 kg no-gi division.

After the win, Nilsson announced his retirement from Submission Wrestling with the reason that he wanted to focus more on his MMA career and his family.

[12] Nilsson won in devastating fashion as he submitted Gluhak in one minute via rear-naked-choke and soon got a new fight offer from The Zone FC.

30 seconds into the bout Sokolis was taken down to the ground by Nilsson with a slam so hard that the particle board under the canvas broke.

After taking the fight to the mat Nilsson quickly mounted his opponent and secured a triangle choke for the tapout after a scramble.

[16] On February 11, 2012, Nilsson defeated The Ultimate Fighter finalist Tom Speer via second round arm triangle choke at Cage Warriors Fight Night 3.

Nilsson's next fight was against Russian fighter Alavutdin Gadjiev in Strength & Honor Championship 5 which took place March 24 in Geneva, Switzerland.

On May 6, 2012, Nilsson fought fellow Swedish top middleweight prospect Tor Troéng on The Zone - Demolition in Gothenburg, Sweden.

[21] On February 29, 2012, it became official that Nilsson signed an exclusive multi-fight deal with London based MMA organisation Cage Warriors.

[23] Nilsson was expected to fight Denniston Sutherland on Cage Warriors 50 which took place the 8 of December 2012 in Glasgow, Scotland, but had to withdraw due to a torn LCL.

[24] Nilsson fought for the first time in almost a year when he faced British fighter Chris Scott the 13th of April 2013.

[33] Nilsson was nominated in two categories at the 2012 Swedish Martial Arts Gala, Kampsportsgalan 2012, Champion of the Year and People's Award.