Ken Breitenbach was selected in the second round, 35th overall by the Buffalo Sabres in the 1975 NHL Amateur Draft from the OHA's St. Catharines Blackhawks.
Breitenbach grew up in Welland, Ontario, a town of 50,000 just south of St. Catharines. At the age of 16, he joined the Welland Sabres of the OHA Junior B league in 1971-72, scoring six goals and 24 points in 34 games.
In 1972-73, Breitenbach joined the St. Catharines Blackhawks after a strong training camp. In his rookie year, he played in 37 games, scoring a goal and nine points. In 1973-74, the Blackhawks won the Ontario championship and earned the right to represent the league in the Memorial Cup in Calgary in the three-team round-robin tournament. The Hawks had a strong junior club, boasting the likes of scoring stars Rick Adduono, Dave Gorman and Wilf Paiement up front, with Rick Hampton, Breitenbach and Garry Lariviere providing a steadying influence on the defense. They also had stellar netminding from Bill Cheropita between the pipes. It looked good for the Hawks, until they faced the WHL champion Regina Pats, led by the likes of defenseman Greg Joly and future NHL stars Clark Gillies and goalie Ed Staniowski. In the end, it was the Pats who walked away with the title, beating the Quebec Remparts in the final.
Breitenbach returned for another year in St. Catharines, but the team was gutted, having lost Gorman and Lariviere to the WHA's Phoenix Roadrunners and Wilf Paiement to the NHL's Kansas City Scouts and Rick Hampton to the California Golden Seals. Cheropita was back in goal, but his wayward partying often got in the way of his on-ice performance, and the club spiralled downwards towards the bottom of the league in just one short year. In 65 games, Breitenbach scored seven goals and 37 points.
During his first year as a pro, Breitenbach spent 57 games with the AHL's Hershey Bears but was inserted into the Buffalo Sabres lineup on seven occasions in 1975-76 campaign. The following year he dressed for 31 games with the Sabres, tallying five points. He missed the entire 1977-78 season after breaking his leg in training camp in September. Breitenbach attempted a comeback in 1978-79, and although he did play in 30 games, he realized he could not continue. The bright spot, however, was that Breitenbach did score his one and only NHL goal that year and finished with nine points. In a 68-game NHL career, he had a goal and 14 points.