Prior to being elected, Sendzik was the general manager of the Greater Niagara Chamber of Commerce.[4] He had been with the Chamber of Commerce for seven years. Prior to this, he founded Vines Publishing, a publishing company specializing in wine and travel, including Vines magazine.[6] He sold the company in 2005.[3] He also served as president of the Niagara Wine Festival.[7] He holds a B.A. from Wilfrid Laurier University and a master's degree from McGill University.[3]
Sendzik was first elected as mayor in 2014 on a platform of youth retention, employment diversification, and attracting well paying jobs.[2] The position was an open one with the previous mayor, Brian McMullan retiring.[8] Sendzik defeated future NDP MPP Jeff Burch, winning 40% of the vote to Burch's 35%. In his first term as mayor, the city prepared for the construction of a 19-storey condominium building, the first of its kind in the city, part of the city's transition into both a bedroom community and the "urban centre" of the Niagara Region.[9]
He was re-elected in 2018 running on a record of economic development and investing in infrastructure.[10] He was re-elected, winning 72% of the vote. After being re-elected, one issue Sendzik had to deal with were the layoffs at General Motors, one of the largest private sector employers in the city.[11] Also during his second term, St. Catharines experienced a housing boom after increased GO Train connections to the Greater Toronto Area.[12]