Career
His last club was IF Brommapojkarna. He started out his career at local outfit IF Brommapojkarna before moving to Delsbo with his family at age 5. A few years later he returned to his native club with which he pursued a career taking him from the youth ranks all the way up to the senior team
In 2003 he left for Danish Superliga side AGF. He became a regular there until the winter of 2004/2005 when he told his adviser he wanted to leave.
His stated desire was to play for his father"s old team and in March 2005 he signed a three-year contract. He quickly became a regular for the relegated 10-times Swedish champions as a central defender.
But he also became joint second top scorer in the team for the 2005 season by scoring seven goals. Many came through set-pieces with Carlsson"s ability to score with his head proving a deciding factor.
Carlsson is now a successful part of the 2006 squad which is within reach of claiming a shock 11th championship title.
During the 2007 season AIK announced they will not offer Nicklas a new contract, which went out after the season. And on 31 October he signed a three-year deal with Gothenburg side IFK Göteborg. 2010 his contract with IFK Göteborg ended and did not get renewed.
On 1 December 2010 he signed a contract for his first club IF Brommapojkarna.
He retired on 5 November 2012.