He scored 22 points in combination with 172 penalty minutes in his first season with the team and helped them win the Memorial Cup.

Lajeunesse started off in Detroit's farm team, the Fort Worth Wings of the Central Hockey League.

He spent time with the Tidewater Wings of the American Hockey League and Fort Worth, while suiting up for seven games in Detroit.

He contributed 20 penalty minutes in those seven games without scoring a point and finished the 1971–72 season back in Fort Worth where he helped with a short playoff run.

He continued playing in the minor leagues with Tidewater (now renamed the Virginia Wings) in 1972–73 before being called back to Detroit to fill in for injuries.