In 1944, Lallo began his professional hockey career as a member of the Boston Olympics of the Eastern Hockey League. Slowly, the 5-foot-9½, 200-pound defenseman climbed the ranks of organized hockey to the International Hockey League. Lallo skated five seasons with the IHL’s Grand Rapids Rockets, earning all-star accolades during the 1954-55 season.
In the fall of 1960, the veteran defenseman joined the Zephyrs, an IHL expansion franchise in Muskegon, serving as player-coach. Lallo notched a career-high 24 goals in 58 games in 1961-62, his second year with the club. Muskegon earned the Huber Trophy that season, presented to the league’s regular season champion, as Coach Lallo guided the Zephyrs to a 43-23-2 record. In playoff action, Muskegon notched an 8-1 mark en route to the Turner Cup, signifying the winner of the IHL’s playoff championship series.

Before the start of the 1964-65 season, Lallo stepped down from his coaching duties to concentrate on his final season of play. His playing days spanned nearly 1,100 games over 21 seasons, including 598 IHL contests. The Montreal native returned to the coaching ranks the following year, guiding the Muskegon club (renamed the Mohawks) to a second Huber Trophy, after a disappointing sixth-place finish in 1964-65. His 1967-68 squad tallied a 43-17-12 regular season mark, and another 8-1 record in post-season play to gain their second Turner Cup. Named coach of the IHL first team all-stars five different times, as well as second team all-star coach on two other occasions, Lallo garnered the March of Dimes Man of the Year award in April 1973.

Lallo parted ways with the Muskegon franchise in March of 1978. In his 17 seasons at the helm, his teams compiled a 600-443-93 regular season record. Muskegon made the playoffs in 13 of those seasons, notching a 50-50-2 post season mark, two Turner Cups and seven Huber Trophies.
He retired from hockey following the 1980-81 season, after three seasons as coach of the Fort Wayne Komets of the IHL.