The new competition will see the northern hemisphere welcome South Africa's former Super Rugby sides - the Bulls, the Sharks, the Lions and the Stormers - from April, in what promises to whet the appetite ahead of the 2021 British and Irish Lions tour to the Rainbow Nation.
The current Guinness PRO14 season will conclude on March 27 with a final between the top team in each conference at the home of the highest-ranked club; prior to this, rounds 12-16 will be played between 20 February and 20 March. Dates, times and broadcast information for these fixtures will be shared in the new year.
Teams will then reconvene for the start of the Guinness PRO14 Rainbow Cup in April, with the 16 teams split into two conferences; each conference will contain two South African , two Irish, two Welsh, one Italian and one Scottish team, with each club playing against its conference rivals either home or away.
The two conference-topping teams will contest the inaugural Guinness PRO14 Rainbow Cup Final on 19 June.
Glasgow Warriors Head Coach Danny Wilson said: "We're looking forward to the prospect of going up against South Africa's famous rugby franchises in 2021. Their style of play and proud rugby traditions will add a new and exciting dimension to the Guinness PRO14 Rainbow Cup. In the mean time we're looking forward to getting back onto the field in the new year for our 1872 Cup derby games and the remaining league rounds from January to March."
Martin Anayi, CEO of PRO14 Rugby, said: "At a time where our sport has faced its greatest challenge, we have promising news about the future of our tournament and the strengthening of our partnership with South African rugby.
"As our teams and unions have worked relentlessly to keep our sport alive, we have been tasked by our shareholders to map out a future that provides greater certainty and allows for a more harmonious calendar between club and country.
"It was vital that we worked with all parties to ensure our current 12 teams had a clear road towards European qualification ahead of introducing any new teams. With a British & Irish Lions tour to come it is hard to think of anything better to whet the appetite than the best players from the Celtic regions competing against World Cup-winning Springboks in the Guinness PRO14 Rainbow Cup."
Jurie Roux, CEO of SA Rugby: "The inclusion of South Africa's 'Super' Teams in the Rainbow Cup is a major step in confirming our place in the expanded Guinness PRO14 competition. This is a once-in-a-generation, watershed moment for South African rugby.
"After so much turmoil and uncertainty in 2020, the prospect of a return to top-flight international domestic competition is one to which we all can all look forward with real excitement."