When the NHL decided to expand in 1967. Riley had offers to be general manager from the Pittsburgh Penguins, St. Louis Blues and the Philadelphia Flyers. Riley decided on Pittsburgh, because of its proximity to his family in Toronto, and was hired by the Penguins' owner Jack McGregor, who also served as the team's president and CEO. As the Penguins' general manager, Riley helped pick the team's nickname and the team's uniform colors, which were Columbia blue, navy blue and white. He then hired George "Red" Sullivan as the team's first coach. During the 1967 Expansion Draft, the NHL made it hard for the new clubs, by limiting the number of quality players the established Original Six teams could leave unprotected in the expansion draft. The league also placed the two developmental teams controlled by each of the established teams off-limits. The expansion teams would have to depend mainly on free agents signed by Riley from the Pittsburgh Hornets, who were the defending AHL champions. Riley signed the Penguins' first player Les Binkley, who would play for the Penguins for parts of five seasons. Former New York Rangers star Andy Bathgate, who would lead the West Division in scoring at age 34 was selected late in the draft by Jack McGregor. The Penguins payroll in their first season was $350,000. Under Riley, the Penguins finished fifth in the league their first 2 seasons. In their third year, the Penguins placed second in the West Division and beat the Oakland Seals, 4-0, in the first round of the playoffs before losing to St. Louis in six games in the league semifinals. In the third round of the 1969 NHL Draft, Riley selected forward Michel Briere. Briere had a successful rookie season and looked to be a player that the Penguins could be built around. He was critically injured in a car crash in Quebec a few weeks after the season, however, and remained in a coma for 11 months before he died. He was 21. During those 11 months, Riley was a frequent visitor of his at the hospital.
Post hockey
In January 1974, Riley was replaced as the club's general manager by his assistant, Jack Button. He remained with the team, helping as a scout. Decades later, he worked as a replay judge during Penguins' games at Mellon Arena and as a consultant to the IHL and AHL into his 80s. Riley was an active member of the Penguins' Alumni Association. In 2000, Riley was elected to the Pittsburgh Penguins' Hall of Fame. He was in attendance as the "Honorary GM" at 2011 NHL Winter Classic Alumni Game at Heinz Field between alumni of the Penguins and Washington Capitals. Riley lived in South Hills with his daughter, Barbara, since his wife died in 1988. He jogged daily from his 30s into his 70s. He maintained a friendship with fellow former-Penguins' general manager Eddie Johnston and still attended Penguins' games into his 90s. The locker room at the Penguins' current arena, Consol Energy Center, contains a mural in the team's locker room which features Riley for his contribution to the franchise. Riley died on July 13, 2016 in Scott Township at the age of 97. His death occurred less than a month after the Penguins' franchise, that he had helped build, won its fourth Stanley Cup title. In a press release the Penguins stated that "We are deeply saddened by the passing of Jack Riley." The Penguins added that the organization was "built on the shoulders of hard-working people like Jack, and the loss hits home as the team’s 50th anniversary is set to be celebrated during the upcoming campaign."
