Richard Mulhern was selected eighth overall in the 1975 Amateur Draft. In his rookie season, 1976-77, the young Mulhern was drawing comparisons to Bobby Orr. After 43 games, he had posted 32 points and was projected to have 59 by the end of the season. Unfortunately, his paced slowed over the next 36 games as he added only 12 more points to his total. Still, it was enough to make him the sixth rookie defenseman to pass Orr's first year record for defencemen.
Mulhern was a product of the Quebec Major Junior system. In his first year with Sherbrooke, he made the second team all-star. At the end of his QMJHL career he had was named a first team all-star based on a 90-point season.
At the start of the 1975-76 season, Mulhern made the Atlanta Flames out of training camp. He found the transition from junior to the NHL more difficult than he expected and was sent to Tulsa of the CHL after just 12 games. The 44 points of his rookie campaign did open some eyes. Not only did he surpass Bobby Orr's rookie numbers, but his 12 goals set a Flames record for goal scoring by a defenseman. His sophomore season removed the comparison to the Boston Bruin great as Mulhern slipped back to 32 points. His nine goals still led all Atlanta blueliners.
Atlanta traded the big, mobile defenseman in the middle of 1978-79 to the Los Angeles Kings. His highlight in the second half was a game-tying goal, his last in the NHL. In the off-season, Mulhern underwent back surgery. He played only 15 more games in a Kings uniform before being traded again.
Richard Mulhern played parts of the next two seasons with the Toronto Maple Leafs and Winnipeg Jets
before retiring as a player in 1981.