As a youth, Pelech played in the 2001 Quebec International Pee-Wee Hockey Tournament with a minor ice hockey team from Vaughan. Pelech played four seasons in the Ontario Hockey League with the Sarnia Sting, London Knights and Belleville Bulls. In 2007, he was assigned to the Quad City Flames of the American Hockey League. He was recalled by the Flames on April 4, 2009, making his NHL debut that night against the Minnesota Wild. Pelech recorded his first career point, an assist, three nights later against the Los Angeles Kings. He joined the Abbotsford Heat for the 2009–10 season when the Flames relocated their AHL team. He was sidelined in January 2010 with a blood clot in his arm, an ailment team doctors initially feared was season ending. Pelech recovered in time to join the Heat for their playoff run, appearing in all 13 of the team's post-season games. Pelech appeared in 59 games for the Heat in 2010–11, scoring 3 goals, 2 assists and adding 198 penalties in minutes. The Flames chose not to offer Pelech a new contract following the season, making him an unrestricted free agent. Pelech signed with the San Jose Sharks, spending the season with their AHL affiliate, the Worcester Sharks. He appeared in 59 games during the 2011–12 AHL season, where he scored eight points and had 168 PIM. He was an alternate captain in Worcester, and was voted the team's "unsung hero". Pelech, who was moved to the right wing and developed into an enforcer role in the Sharks organization, returned to Worcester for the 2012–13 season where he recorded seven points in 58 games and added a career-high 238 PIM. He also appeared in two games with San Jose. The Sharks again re-signed Pelech to a one-year contract prior to the 2013–14 NHL season. Following a training camp in which he worked to prove he could be more than just a fighter, Pelech was initially assigned to the San Francisco Bulls of the ECHL, but was recalled to San Jose for the season opening game when the Sharks' coaching staff felt the team required a greater physical presence. He scored his first NHL goal – the game winner – against goaltender Roberto Luongo in a 4–1 victory over the Vancouver Canucks on October 10, 2013. On May 13, 2015, Pelech agreed to a one-year contract with German outfit, Schwenninger Wild Wings of the DEL. He made 49 appearances in his sole season with the Wild Wings, tallying eight goals and twelve assists. In April 2016, Pelech inked a two-year deal with fellow DEL team Hamburg Freezers. However, the Freezers folded the following month. In September 2016, he signed with the Graz 99ers of the Austrian Hockey League, After one season in Austria, Pelech moved back to Germany for the 2017–18 season as he inked a one-year deal with ERC Ingolstadt on May 23, 2017. On July 10, 2019, Pelech moved to the United Kingdom's Elite Ice Hockey League, signing for defending league champions the Belfast Giants.
