Toulouse Olympique XIII will be joining Hemel Stags in Kingstone Press League 1 next season.
The current French champions will make the competition a 15-team league, which will see a new structure put in place, introducing a bye round for every team.
Toulouse have previous experience of playing in the domestic competition having been part of the old Co-Operative Championship from 2009 to 2011.
Toulouse Olympique chairman, Bernard Sarrazain said: “We would like to thank the RFL and its clubs for accepting us into this competition.
“It will mean big changes for us, with huge financial and sporting challenges, however we thoroughly believe that, after winning the French Elite Championship two years in a row, it is a vital step for the development of our club.”
The double French champions have a young talented team (average age 24) with an established player pathway. Their reserve team comprises mainly U21 players and is currently doing well in the French Elite 1 competition.
In 2005 Toulouse became the first French club to reach the semi-finals of the Rugby League Challenge Cup when they defeated Widnes Vikings 40-24. They went on to lose 56-18 to Leeds Rhinos in the semi-final.
Coach Sylvain Houles, who played Super League with Sheffield-Huddersfield, London Broncos and Wakefield Trinity Wildcats said: “I am thrilled with the decision and I cannot wait to start first team pre-season training and of course the competition. There are many changes which we will have to cope with, but I have full confidence in my staff and my players.”
Toulouse will enter the Ladbrokes Challenge Cup in Round Three but will not compete in the iPro Sport Cup.
RFL chief executive Nigel Wood said: “We are delighted to welcome Toulouse Olympique back into the competition. The Board, under the guidance of chairman Bernard Sarrazain and chief executive Cedric Garcia, have worked hard to put together a compelling business case that is predicated on working in partnership with the French Federation.
“Their plan is to ensure there is tangible, coordinated and strategic growth from the impetus of Toulouse’s entry into League 1 that will positively impact on the domestic and national footprint in France.”