Mylläri started in the Ski Jumping Continental Cup (COC) from the 1996/97 season . In his first season, however, he reached only 127th place in the overall standings with 15 points. In the 1997/98 season he reached the 77th place in the overall COC ranking with 153 points. At the Junior World Championships in 1998 in St. Moritz , Switzerland , he won the bronze medal in team jumping with Pekka Salminen , Hannu Alakunnas and Matti Hautamäki . In the 1998/99 season he achieved 55th place with 218 points and thus the best placement of his career in the overall Continental Cup ranking. At the 1999 Junior World Championships in Saalfelden , he won the silver medal in team jumping with Veli-Matti Lindström , Pekka Salminen and Matti Hautamäki. Because of this success, he was part of the team for a jumping in the Ski Jumping World Cup for the first time four weeks after the Junior World Championships on March 4, 1999 . In Kuopio he jumped from the large hill to 45th place. Two days later he reached his first World Cup points with 26th place in Lahti. Despite this, this was his last World Cup competition. After another unsuccessful season in the Continental Cup, Mylläri ended his active ski jumping career in 2000.