After playing for future Montreal Canadiens coach Scotty Bowman with the OHA junior Peterborough Petes, Roberts was signed by the Canadiens and turned pro with the Montreal Royals minor league team in 1959.

In the 1964 season, he saw his first NHL action with Montreal and remained the next several seasons, winning two Stanley Cups before becoming the first selection of the St. Louis Blues in 1967 NHL Expansion Draft.

He was known for his defensive skills and often used as a "shadow" against high scoring enemy forwards.

On October 22, 2024, the St. Louis Blues announced Roberts would be inducted into the team's Hall of Fame in January, 2025 along with Wayne Babych and Curtis Joseph[1] Roberts died on October 23, 2015, of cancer, which had been diagnosed weeks prior.

[2][3] On October 27, 2015, the St. Louis Blues announced team members would wear helmet decals for the home stand that read "JR" in the lower left corner to honor Roberts.