[10] By February 2017, a total of nine amateur rugby union organizations including the Austin Huns, Dallas Griffins, Glendale Raptors, Houston Strikers, Kansas City Blues, Minneapolis, New Orleans RFC, Rugby Utah and the Seattle Saracens, announced their intentions to form a professional league to begin play the following year.

[17] The first regular-season game in Major League Rugby history was held on April 21, 2018, when the Houston SaberCats hosted the New Orleans Gold.

In addition to Rugby United New York, the Toronto Arrows joined the league ahead of 2019 season as the first Canadian team in MLR.

Three further American clubs began play in 2020: the New England Free Jacks, Old Glory DC, and Rugby ATL.

Later in April, RUNY announced the signing of French international Mathieu Bastareaud on a loan deal from Toulon for the 2020 season.

[19] In October 2019, another major signing was made when it was announced that All Blacks international and multiple World Cup winner Ma'a Nonu would join the San Diego Legion for the 2020 season.

[20] The following December saw another World Cup winner sign with the league, namely South Africa prop Tendai Mtawarira with Old Glory DC.

[24][25][26] At the end of the 2022 regular season, MLR announced that the Giltinis and the Gilgronis—both owned by Adam Gilchrist, co-founder of F45 Training—were disqualified from the playoffs due to a violation of league rules, allegedly including salary cap issues.

[32][33][34] In November 2023, the Toronto Arrows announced they would cease all operations following the death of founder Bill Webb and a failure to secure new investors.

[39] In advance of the 2025 season, several trial rules were announced, all designed to reduce the number of scrums in matches, in order to speed up the game.

The move drew criticism from fans and commentators, with some remarking that the changes would hinder the development of the sport and international competitiveness.

[45] The Houston SaberCats, New Orleans Gold, San Diego Legion, Seattle Seawolves, and Utah Warriors have been a part of Major League Rugby since its founding in 2018.

Their announcement explained their withdrawal by saying that "our greater responsibility lies in the development of American players who can win the World Cup for the United States.

[55] On October 25, 2022, Major League Rugby announced that 12 teams would compete in the 2023 season, but that neither the Austin Gilgronis, nor the LA Giltinis will participate.

[56] On November 27, 2023, Major League Rugby announced that the Toronto Arrows would cease all operations, and not compete in the 2024 season.

[35] The Arrows had sought new funding following the death of their CEO, Bill Webb, but were unable to guarantee the new backers in time.

Major League Rugby players include those drawn from North American clubs, as well as foreign signings.

Seattle's matches were carried on Root Sports Northwest and all Colorado and Utah games were hosted on AT&T SportsNet Rocky Mountain.

[63] Due to the COVID-19 pandemic, MLR adjusted its 2020 season schedule and turned its attention to ensuring the league would rebound with a strong showing in 2021.

[104] George Killebrew reported that in 2022 an additional 70,000 tickets were sold compared to the 2021 season, with crowd averages remaining around 2,000 per game.

[90] Commissioner/CEO Deputy Commissioner The Gem Garden in San Marcos, California, makes all MLR Championship rings, as of 2018.

[109] On November 1, 2023, MLR announced a 3-year partnership with Italian sportswear brand, Kappa, as the official kit partner of the league, beginning with the 2024 season.

OVAL3 plans to provide "world-class immersive experiences" and Web 3.0 engagement to rugby's rapidly-growing North American fanbase.

[114] On October 6, 2023, MLR signed a partnership with Legends to lead sponsorship sales and commercial outreach.