He played with Chicago State University from 1975-79. Undrafted by the NHL, he signed as a free agent by the Chicago Blackhawks. Janecyk played for four seasons in the minor pros, winning top goalie awards in 1979-80 and 1981-82. He finally got a chance with the Blackhawks in 1983-84, appearing in 8 games that season. In 1984 Janecyk was traded to the Los Angeles Kings and became a regular for two seasons. But his ice time was reduced as the Kings accquired Darren Eliot to back up Roland Melanson. After a couple of seasons with the New Haven Nighthawks Janecyk retired in 1989.