Career
He Currently plays with Ilves in the Finnish Liiga. Niinimäki was selected by the Edmonton Oilers in the first round (15th overall) of the 2002 National Hockey League Entry Draft. Niinimäki spent the 2004-2005 season with the Edmonton Road Runners and Ilves, and signed with Jokerit for the 2005-2006 season.
After a disappointing fall season, Niinimäki was released from his contract with Jokerit in January 2006, and hired by JYP for the rest of the season.
After the 2005-2006 season, Niinimäki moved to Sweden and played for Elitserien side Luleå High Frequency in 37 games. Niinimäki also played for the German DEL team Krefeld Pinguine.
The tenure in Germany lasted for 9 games plus 2 games in the playoffs. After completion of the 2006-2007 season Niinimäki returned to Luleå but was released during September 2007.
Niinimäki was acquired by Swiss Nationalliga A team The Human Context Davos, but in January 2008 he returned to HPK.