The Rugby Football League have confirmed the registration of Folau with the French side will "not be prevented".
Catalans today (Tuesday) announced Folau has joined them on a one-year contract.
The 30-year-old winger was sacked by Australia Rugby last year, following homophobic posts on social media.
Wigan Warriors immediately announced their round six game against Catalans, in March, will be Pride Day, as the Warriors "support the LGBTQ+ community".
A statement from Elstone said: "Super League deplores the homophobic comments Israel Folau has made in the past, which squarely contradict our sport’s core values.
"I have sought the opinion of informed voices connected to our game and the majority share my disappointment that one of our clubs has chosen to sign him.
"There is a strong feeling that the decision to sign him lets down many people connected to our sport.
"I made Catalans Dragons aware of those views."
But he confirmed: "Super League does not have the authority to veto the registration of players and is satisfied by the due diligence carried out by the Rugby Football League.
"Israel Folau is a free-agent, who has the right to work and he has not been charged or found guilty of any criminal offence.
"Catalans Dragons has assured Super League that strict guidelines are in place to prevent the player from repeating his comments.
"They have also assured us that his contract will be terminated immediately should he do so."
In its own statement, the RFL said: "This is a difficult decision, as the RFL places a high value on the sport’s reputation in prioritising inclusion and diversity – and deplores the player’s previous comments.
"However the moral responsibility for deciding whether to sign a player sits with individual clubs.
"The player has not been charged or found guilty of any criminal offence.
"However distasteful his previous comments, we don’t believe that, under our current regulatory framework, these can prevent his participation in the sport."
It added: "We have sought and received reassurances from both the player and the club regarding future behaviour.
"The RFL has taken and will continue to take action where any player breaches expected standards of behaviour while registered with a club and comments that conflict with our commitment to inclusion and diversity across the game will not be tolerated."
Folau played league for Melbourne Storm and Brisbane Broncos before switching codes in 2013.
He told Dragons' website: “I acknowledge the views expressed by Super League and the Rugby Football League.
"I'm a proud Christian, my beliefs are personal, my intention is not to hurt anyone and I will not be making further public comment about them.
"I look forward to my return to the great game of rugby league with the Catalans Dragons.”
Dragons chairman Bernard Guasch said: “We want to give Israel a new opportunity to shine on the pitch.
"We do not support or agree with Israel’s previously expressed and controversial views which are based upon his sincerely held religious belief.
"We do not share or condone those views and we are totally committed to our club and our sport being open and welcoming to everyone.
"We do not believe that those views should be publicly expressed, especially by a high-profile sports person.
"We have a signed agreement with the RFL. Any transgression will trigger an immediate termination of Israel’s contract and a substantial fine for the club.”