Gendron began his career with the New York Rangers after playing one season with Providence of the American Hockey League. Following his third season in New York, Gendron was selected by the Boston Bruins in the 1958 NHL Intraleague Draft. He then played three seasons for the Bruins before being traded to the Montreal Canadiens, his hometown team, for Andre Pronovost on Nov. 27, 1960.
Gendron finished with 21 points (nine goals, 12 assists) in 44 games for the Canadiens in 1960-61, his only season in Montreal. He returned to the Rangers the following season before playing again with the Bruins from 1962-64.
Gendron spent the next four seasons playing for the Quebec Aces in the AHL. He had 73 points (28 goals, 45 assists) in 68 games in 1966-67, when the Philadelphia Flyers purchased the Aces to be their AHL affiliate. The Flyers then acquired Gendron's NHL contract.
Gendron played in only one NHL game with the Flyers the following season, Philadelphia's first in the League, but he made an impact playing left wing on a line with center Andre Lacroix and right wing Leon Rochefort in 1968-69. That season, he had an NHL career-high 55 points (20 goals, 35 assists) in 74 games.
Gendron scored at least 20 goals in each of the following two seasons before getting 19 points (six goals, 13 assists) in 56 games in 1971-72, his last in the NHL. He then played two seasons with the Quebec Nordiques of the World Hockey Association.
After his playing career, Gendron coached Quebec for two seasons from 1974-76, going 96-59 with four ties in 159 regular-season games. He was also 9-11 in 20 postseason games, including leading the Nordiques to the Avco Cup Final in 1975, when they were swept by the Houston Aeros.
