South African rugby bosses voted Tuesday in favour of the Bulls, Lions, Sharks and Stormers seeking entry to an expanded PRO14 competition.
The four franchises were part of Super Rugby until the coronavirus pandemic this year ended the competition in its five-nation format.
New Zealand and Australia are planning domestic or trans-Tasman competition, which sidelines the South African sides and the Argentine Jaguares. The Japanese Sunwolves played their final season in the competition in 2020.
"Our members are excited about the prospect of closer alignment with PRO Rugby and seeking a northern hemisphere future," said SA Rugby chief executive Jurie Roux.
"However, we would not have been taking this decision but for actions elsewhere," he added, referring to the decisions of New Zealand and Australia.
SA Rugby president Mark Alexander said: "These are extraordinary times. If this had been an ordinary year, we would not have had this meeting.
"We needed to take radical steps to avoid financial meltdown because of the coronavirus pandemic crisis."
The Cheetahs and the Kings became the first South African sides to play in Europe when the PRO12 was expanded in 2017 to include them after they were dumped by Super Rugby.
In the likely event of the Bulls, Lions, Sharks and Stormers joining a 'PRO16', there would be no place for the Cheetahs while the Kings recently went into voluntary liquidation.
SA Rugby favours the Cheetahs being included in a new Australasian competition, but did not give details.
Given that many New Zealand and Australian players complain of long flights, big time differences and jet leg in Super Rugby, the Cheetahs plan could be difficult to achieve.
- Committed to SANZAAR -
Roux said SA Rugby remained committed to the SANZAAR (South Africa New Zealand Australia Argentina Rugby) partnership and competing in the annual Rugby Championship.
PRO14 consists of four teams each from Ireland and Wales and two each from Italy, Scotland and South Africa.
South Africa director of rugby and 2019 World Cup-winning coach Rassie Erasmus said there would be a number of advantages if the 'big four' joined PRO rugby.
"The first benefit is for rugby followers who will be able to watch matches at normal times," he said during a virtual media conference.
South Africans have had to watch matches from New Zealand and Japan before breakfast, from Australia in mid-morning and from Argentina after midnight.
Turning to players and coaches, he said: "You can get on a plane, sleep on it and play the next day.
"That is nice from our planning and for broadcasters as well. There are regular flights that you can get to every destination."
The widest time difference between South Africa and Britain and Ireland is two hours for six months each year, compared with 11 hours for New Zealand.
Erasmus said there would also be some disadvantages in swapping Super Rugby for the PRO version, but did not elaborate.
Not tackling New Zealand franchises like the All Blacks-packed Canterbury Crusaders -- arguably the strongest in the world -- will be one obvious drawback.