By 1947, Ronty got his first crack at the Boston Bruins line-up, splitting the season between Boston and Hershey Bears of the AHL. The following two seasons brought him full-time action with the Bruins. While centering wingers Johnny Peirson and Ken Smith, Ronty finished 5th in league scoring in 1948 and 1949, topping the 20-goal plateau on both occasions.
But in 1955, Ronty let a comment slip that he was considering retirement. The Rangers management was quick to respond, shipping his rights to the Montreal Canadiens. The Canadiens were in need of a quick fix to fill the gap in the wake of Rocket Richard's suspension for a stick-swinging incident with the Bruins' Hal Laycoe. Ronty played four games for the Habs, but refused to return the following season because a secure contract was not offered in advance.
Ronty played in 488 NHL games, with 101 goals and 211 assists.