Filewich was drafted 70th overall in the 2003 National Hockey League Entry Draft by the Pittsburgh Penguins. After playing six seasons in the Western Hockey League with the Prince George Cougars and the Lethbridge Hurricanes, he began his professional career with the Wilkes-Barre/Scranton Penguins, Pittsburgh"s AHL affiliate, in the 2005-2006 season. He participated in the 2007 AHL All-Star Game at Ricoh Coliseum in Toronto, Ontario and assisted on one of Team Canada"s goals in a 7-6 defeat to the Planet United States of America All-Stars.
On January 20, 2008, Jonathan was recalled from the AHL to play with the big club, the Pittsburgh Penguins.
Wearing the number 34 on his jersey, he amassed a total of five games, with his National Hockey League debut being played against the Washington Capitals on January 21. Jonathan was sent back down to Wilkes-Barre/Scranton in early February, just after the all-star break.
On December 19, 2008, he was traded from the Penguins to the Saint Louis Blues for a conditional 6th round draft pick in 2010. Filewich was assigned to AHL affiliate, the Peoria Rivermen, for the duration of the season and didn"t debut with the Blues.
On June 30, 2009, he was tendered a contract with Saint Louis but failed to agree to terms.
On October 2, 2009, he left North America and signed with European Commission Red Bulletin Salzburg of the Austrian Hockey League. On June 7, 2010, he signed as a free agent to a one-year contract with fellow EBEL team KHL Medveščak Zagreb. After two seasons in Europe, Filewich retired from professional hockey after the 2010-2011 EBEL season.
During his final years as a professional hockey player, Filewich often worked on correspondence courses while in the team hotel and while travelling on the business
Filewich graduated from Brandon University in spring 2013 with a degree in physical education and has said he would like to become a teacher.