NFL Growlers

The search for a new professional hockey team for St. John's began after the Montreal Canadiens announced in July 2016 that their affiliate, the St. John's IceCaps of the American Hockey League (AHL), would move to the newly constructed Place Bell arena in Laval, Quebec for the start of the 2017-18 season. Danny Williams, from the incumbent franchise, stated his intention to find a replacement.

From that point two rival groups formed: the operators of the St. John's Edge basketball team, which played at the Mile One Centre, who wanted a Quebec Major Junior Hockey League (QMJHL) franchise for the arena; and another, led by local businessman Dean MacDonald and Glenn Stanford of the former IceCaps, who were looking for an ECHL team.

The ECHL franchise was conditionally approved but was delayed in late January 2018 after the dispute with the St. John's Edge ownership group over arena rights went to arbitration. After the lease issue was settled, the ECHL officially approved St. John's application on March 13, 2018, placing the team in the North Division of the Eastern Conference for the 2018-19 season. The ECHL ownership group reportedly created a partnership with the Toronto Maple Leafs, which would bring the organization back to St. John's for the first time since the team relocated their AHL affiliate, the St. John's Maple Leafs, to Toronto in 2005. The affiliation was confirmed on June 14. Among the names considered for the new franchise were Shamrocks, Storm, Regiment, and Newfoundland Growlers. The team announced its name as the Newfoundland Growlers on May 22. The name refers to the Newfoundland dog, specifically the World War I mascot of the Royal Newfoundland Regiment, Sable Chief. Ryane Clowe, a Newfoundland native, previously an assistant coach with the New Jersey Devils, was named head coach on June 20. John Snowden was added as assistant coach on July 19 after serving in the same capacity for the Maple Leafs' previous ECHL affiliate, the Orlando Solar Bears.

The Growlers played their first game on October 12, 2018, a 3–2 win over the Florida Everblades in front of a sold-out arena. In January 2019, Clowe stepped down due to health concerns and was replaced by assistant coach John Snowden. The Growlers finished the season first in their division with 94 points. The Growlers then advanced to the finals of the 2019 playoffs defeating the Toledo Walleye in six games to win the Kelly Cup. The Growlers were the second team after the 1989–90 Greensboro Monarchs to win the ECHL championship in its first season of operations. They were also the first Canadian team to win the Cup.

The Growlers did not defend their title in 2020 as the playoffs were cancelled due to the onset of the COVID-19 pandemic. The club then voluntarily suspended operations for the 2020–21 ECHL season due to ongoing pandemic travel restrictions. In the 2021 offseason, head coach John Snowden was hired by the Growlers' AHL affiliate, the Toronto Marlies, as an assistant coach with Eric Wellwood later named head coach for the 2021-22 season. With Wellwood unavailable in February 2022 due to COVID-19 protocols, the Growlers hired Danielle Goyette as a temporary assistant coach, making Goyette the first woman to coach an ECHL team.

2021 arena dispute

In July 2021, co-tenant of Mile One Centre, the St. John's Edge basketball team, were not given the option to renew their lease despite being in negotiations with the Growlers ownership, Deacon Sports and Entertainment (DSE), to purchase the Edge. This led to a dispute between DSE and the City of St. John's as the Growlers still needed to renew their lease agreement as well, which they did, signing a three-year agreement in August 2021. However, the operations of the arena was continued to be criticized by DSE and tickets were not being sold a week before their first scheduled home game of the 2021–22 season.

On October 27, 2021, citing workplace harassment of arena employees, the city voted to evict the team, which elicited the threat of a lawsuit from DSE. A third-party investigation was undertaken. The Growlers initially scheduled their first six home games for the Coca-Cola Coliseum in Toronto, the home of their AHL parent club, the Toronto Marlies, in case they could not secure a local arena. They subsequently came to an agreement with the nearby town of Conception Bay South to play their first six games at the CBS Arena. On November 18, DSE and the city of St. John's came to an agreement to play the rest of the season at the Mile One Centre, renamed Mary Brown's Centre, in early November.

End of operations

On April 2, 2024, the Growlers were terminated by the ECHL effective immediately, for failure to fulfill league bylaws. Reportedly, both the Growlers and their sister team, the Trois-Rivières Lions, had been experiencing financial difficulties whereas the ECHL assumed transitional ownership of the Lions pending the franchise's sale to new owners. As a result of cessation, all eligible Growlers' players signed to a standard player contract were released as unrestricted free agents, allowing other league members to sign up to two former players. Contrarily, all Growlers players under an AHL or NHL structured contract were deemed ineligible to play the six remaining games of the 2023–24 ECHL season.