Former Iron captain Byrne, who left the club this summer after nine years, registered as a member ahead of his benefit match at Glanford Park on Sunday July 29.
The Iron Trust is a democratic not-for-profit organisation which is seeking to establish regular communication between fans and senior management at Scunthorpe United.
It intends to use membership fees to purchase shares in the football club, ensuring that supporters always have a voice in the club.
"Cliff backing us is a brilliant show of support from a player who really understood that fans mean much more to a football club than bricks and mortar," said Tony Gosling, chairman of the trust's interim board.
"We expect other players, past and present, will join us on Sunday as we accept full membership for supporters for the first time.
"We have a unique opportunity to establish a strong voice for fans, and have been encouraged by the backing the club have already given us. We believe we can have a positive long-term impact on this football club.
"Fans are the moral owners of any football club, and our supporters really want to help the club. We can give them the opportunity to do so."
The Iron Trust will have a stall at Sunday's open day, being held at Glanford Park from 12noon, where fans will be able to sign up for the first time.
Membership costs £10 per adult, with a family membership (two adults and unlimited U16s) costing £20. Membership for U16s is £3.
Members will get a small gift, but more importantly will decide on the future of the trust as it builds towards board elections later this year and influence the way the trust will work with Scunthorpe United Football Club to the benefit of all.
Image of Cliff Byrne signing up with interim board secretary John Needham is courtesy the Scunthorpe Telegraph