The 32-year old Dane is an experienced touring car driver; twice winner of the European Touring Car Cup (2007 and 2008) and the Danish Touring Car Championship (2007 and 2009), five race victories and a third position in the 2012 STCC, Nykjær is a familiar face in WTCC.
He competed in two full seasons (2010 and 2011) claiming one podium result and finishing as runner up in the 2011 Yokohama Trophy.
“I’m thrilled to return to action in the WTCC, and especially with NIKA Racing," he said.
"We have gained huge respect for each other in our STCC programme, and we are definitely ready to take this step.
"The WTCC is incredibly competitive, but I think we have some important ingredients in place for a strong campaign.
"I know the majority of the circuits on the calendar, and the Chevrolet Cruze has been the car to beat over the past few years. I’m immensely motivated to get going and I will fight for every tenth, every lap."
Team principal Nicklas Karlsson echoed: “Michel is one of the fastest touring car drivers in the world and we are delighted to extend our relationship with him.
"The combination of driver, car and a highly enthusiastic workforce gives us an encouraging platform on which to build over the season, and hopefully the tools we need to take the fight to our experienced rivals."