Born in Victoriaville, Quebec, P.J. Stock played Tier II junior A with the Pembroke Lumber Kings before moving up to the hometown Tigres of the QMJHL in 1994. After two seasons in Victoriaville Stock then played a year with St. Francis Xavier University before signing with the New York Rangers as a free agent in the fall of 1997.
Stock split his first three pro seasons between the Rangers and the team's AHL affiliate in Hartford before opting to sign as a free-agent with the Montreal Canadiens in the summer of 2000. Upon his arrival with Montreal, Stock was a solid role player for the first quarter of the season, however he was traded to the Philadelphia Flyers shortly after his arrival in Montreal. As a Flyer, Stock continued to play a gritty role and spent the better part of the season with the club, while seeing limited action with its AHL affiliate, the Philadelphia Phantoms. Prior to the 2001-02 season Stock returned to the Rangers, yet shortly after was claimed by the Boston Bruins in the Waiver.
Despite his smallish stature, Stock's hard-nosed style of play, made him a fan-favourite with every team he played with.