Hietanen made his
SM-liiga debut with
HPK during the
2003–04 season, and two years later he became a regular player on the team. He also visited
Pelicans early in his career and was part of the
Finnish national junior team in the
2005 World Junior Ice Hockey Championships. At the time of his SM-liiga debut, he was the first third generation player in the top level of Finnish ice hockey. In 2006 he celebrated the championship with HPK. He scored two goals and an assist in the second final, but HPK suffered its only loss in the series. In 2007, he moved to Sweden to play in the
Elitserien with
Brynäs IF and for the
2010–11 season he signed with
HV71. Hietanen played in the
Kontinental Hockey League (KHL) from 2011 to 2021, first with
Torpedo Nizhny Novgorod and later with
Dynamo Moscow. After 15 seasons abroad, Hietanen opted to return to Finland as a free agent and re-joined their original club, HPK of the Liiga, on an optional three-year contract on 22 April 2022. ==International play==