Renwick was born in Cambridge, Ontario, Canada, and was a fine athlete as a teen, but it was clear he was destined for a career as an executive. He became president of the Galt Hornets, one of the premier senior teams in Canada, from 1966 to 1973, during which time the Hornets won the Allan Cup twice, in 1969 and 1971.
Renwick became a director of the CAHA – the predecessor of Hockey Canada – in 1969 and its Vice President four years later. During that time he was a leader in developing relationships between Canadian club teams and European teams, culminating in December 1972 when Galt hosted a 15-game tournament that included Dynamo Moscow, Timra IK from Sweden, Prague Selects from Czechoslovakia, and three Ontario teams – Galt Hornets, Owen Sound Downtowners, and Kingston Aces.
In 1974, Renwick organized the Wrigley Cup, a national midget tournament whose winner would travel to Moscow for a series of games. The tournament continues to this day under the name Air Canada Cup.
Renwick was elected the president of the CAHA in the spring of 1977. Among his first orders of business were to hire Dave Branch as executive director and to establish a women’s council that would give greater influence to the development of women’s hockey in Canada. He also made facemasks mandatory for all players and helmets mandatory for all on-ice officials.
A year later, Renwick was named to the IIHF Council and in 1979 Murray Costello succeeded him as CAHA president. Renwick, meanwhile, became President of the Senior OHA. He sat on the Council of the IIHF for 20 years and was Vice President from 1984 to 1996, during which time he modernized its accounting practices and took international marketing and sponsorship to new levels.
A special interest of his was the relationship between Canadian and international rules, and to that end Renwick sat on the Rules Committee for several years. In the mid-1990s, he was a key member of the negotiation team that met with the NHL and NHLPA to get the league to participate in the Olympics, and true to his roots he was an energetic supporter of NHL club teams playing in Europe.
In addition to being inducted into the IIHF Hall of Fame in 2002, Renwick was an inaugural honouree of the Order of Hockey in Canada in 2012. The Renwick Cup is awarded annually to the Senior A champion of Ontario, which then goes on to compete for the Allan Cup.