The Pro League is a professional esports league for Rainbow Six Siege, hosted and organized by ESL in association with Ubisoft. The league was announced in January 2016 and began with Year 1 Season 1 on March 4, 2017. The league coincided with Rainbow Six Siege updates before Year 3, with three seasons per year; the fourth being taken up by the Six Invitational. Since Year 3, there are two 6-month seasons per year.
For Year 1, the Pro League featured divisions in both PC and Xbox One, the latter in association with Microsoft. For Year 2, the Xbox One division was cut in favor of expanding the PC Pro League, with the platform moving to the Major League. Challenger League was also introduced as the second best league on the competitive scene and the only path to qualify in Pro League.
The league consisted of two divisions, North America and Europe. Teams played in a round-robin format, playing every other team in a best-of-two, with the top 2 teams proceeding to world playoffs.
At the beginning of the year, Latin America got its own Pro League while Asia Pacific had to wait until Season 3. The format was adjusted to accommodate for the newly added division and production. Teams now play in a GSL Group Stage, with the top two teams proceeding to regional playoffs. Prior to Year 2 Season 3, teams would play in a single-elimination bracket, with the top two teams and the winner of the third-place match proceeding to LAN playoffs for North America and Europe, with only the top two proceeding to LAN playoffs in Latin America. This was again rectified in Year 2 Season 3 where, while teams continue to play in a single-elimination bracket, only the top two teams proceed to LAN playoffs for each division.
For Asia Pacific, there are four regional divisions: Australia & New Zealand, Japan, South Korea, and Southeast Asia. Each division functions similarly to the regular seasons of other divisions, featuring a GSL group stage and a single-elimination bracket, but with the top two teams proceeding to the regional Asia Pacific finals. The Asia Pacific Finals are played on LAN with the top two teams proceeding to the Pro League Finals.
A few weeks before the Six Invitational 2018, Ubisoft and ESL announced a few changes to the competitive roadmap. In Year 1 and 2, Pro League seasons were following game seasons. For this third year, they decided to make Pro League seasons six months long (twice as long as before). With this change, regional Pro Leagues were going back to a round-robin format but this time with best-of-three matches. Top 2 teams of each region still qualify to the world finals. Due to time constraints, Season 7 was a transitional season using the same format as Year 2 while Season 8 was the very first season to last 6 months.
- Ubisoft (2016-01-21). "Rainbow Six Siege Pro League Starting Early 2016".