Steve Zalewski was born on August 20, 1986 in Utica, New York. Drafted 153rd overall in the 2004 NHL Draft by the San Jose Sharks, the Clarkson University graduate made his professional debut for the Sharks' AHL affiliate in Worcester in 2008.
Zalewski spent the majority of the next two seasons with Worcester before finally seeing his first NHL action in October of 2009. In all, he would appear in three games for San Jose during the 2009-10 season.
On February 9, 2011, Zalewski's time in the Sharks organization would come to an end. He was shipped to the New Jersey Devils along with Jay Leach in exchange for Patrick Davis and Mike Swift.