Zettler was drafted 55th overall by the Minnesota North Stars in the 1986 NHL Entry Draft. After two seasons with the North Stars organization, he was claimed by the San JoseSharks in the 1991 NHL Dispersal Draft. On February 1, 1994, the Sharks traded Zettler to the Philadelphia Flyers in exchange for Viacheslav Butsayev. Philadelphia traded him to the Toronto Maple Leafs for a fifth-round pick in the 1996 NHL Entry Draft on July 8, 1995. With Toronto Zettler enjoyed his most productive season in 1996-97, scoring 2 goals and adding 12 assists for 14 points. After being left unprotected by the Maple Leafs he was claimed by the Nashville Predators in the 1998 NHL Expansion Draft. On September 7, 1999, Zettler signed as a free agent with the Washington Capitals. Rob Zettler announced his retirement on August 27, 2002, he finished his NHL career with 569 games, scoring 5 goals and 65 assists for 70 points.
Post-playing career
He had been an assistant coach under Ron Wilson, but was relieved of his duties after Wilson's firing. He has also been an assistant coach for the San Jose Sharks. Zettler also served as colour commentator for Washington Capitals radio broadcasts and provided commentaries on San Jose Sharks radio broadcasts before becoming an assistant coach. While a member of the Sharks coaching staff, he provided insight into games during telecasts with updates before the start of the second and third periods. On March 2, 2012, Zettler was again relieved of his position of assistant coach to Ron Wilson in favour of another position within the Toronto Maple Leafs organization. In July 2012, Zettler was hired by the Tampa Bay Lightning to be an assistant coach with their AHL affiliate, the Syracuse Crunch. After the promotion of Jon Cooper on March 25, 2013, Zettler was named the head coach of the Crunch. On May 10, 2016, the Syracuse Crunch announced the hiring of Benoit Groulx to replace Zettler as head coach of the team. On July 3, 2017, Zettler was hired as an assistant coach for the San Jose Sharks, replacing Bob Boughner, who was hired as head coach of the Florida Panthers on June 12, 2017. When Boughner returned to the Sharks on May 29, 2019, he filled Zettler's position on the staff.
