After spending a year in Tier II Ontario Hockey Association play, Hislop attended the University of New Hampshire under legendary coach Charlie Holt. In Hislop's sophomore year with the Wildcats in 1974, he led the ECAC in assists with 35 en route to the conference title, leading to him being drafted by the Montreal Canadiens in the 8th round of the 1974 NHL Amateur Draft. He followed that performance up with two 66-point seasons, winning conference First All-Star honours in 1975 and 1976 and being named to the NCAA First Team All-American squad in 1976. He finished his collegiate career with 77 goals and 132 assists for 209 points, the leading scorer in Wildcat history to that time, and is currently 4th all-time.
After spending half a season in the minor leagues with the Hampton Gulls, Hislop was signed by the Cincinnati Stingers of the World Hockey Association in 1977. He played three seasons with the Stingers, his best year coming in 1979, when he scored 30 goals and 40 assists for 70 points, chipping in six points in three playoff games.
When the Stingers folded in the WHA-NHL merger, in 1979, Hislop's rights were acquired by the Quebec Nordiques . He was traded midway through the 1980–81 season to the Calgary Flames in exchange for Dan Bouchard; it proved to be his best year in the NHL with a combined 25 goals and 31 assists for 56 points. He played the remainder of his career with the Flames, serving two full seasons before an eye injury sustained in a game against the Islanders on December 1, 1983 forced his retirement.
Hislop finished his NHL career with 75 goals and 103 assists for 178 points in 345 games, adding 61 goals and 102 assists for 163 points in the WHA.
He joined the Flames front office immediately upon his retirement, as an assistant coach, but left hockey for four years until becoming the head coach for the Salt Lake Golden Eagles of the International Hockey League for two seasons starting in 1989. After that, Hislop returned to the Flames, working as a scout and spending three more seasons as an assistant coach until his final retirement in 2004.