Sharks Leagues Club will close on December 15, marking the end of an era that spans half a century.
Some activities have already been transferred to Kareela Golf Club (Sporties) and the proposed amalgamation of the clubs is in its final stages, with members needing to give approval.
Club officials are urging members to rekindle memories by having one last drink or meal before the venue closes to allow a major rebuild as part of stage three of the Woolooware Bay Town Centre development.
The new club is expected to open at the end of 2021 or early 2022.
Among those who gathered for a farewell photo to record the historic event was Jack Stewart, 98, who was president of the leagues club when it opened in 1977, and Paul Gallen, who led the club to its first premiership in 2016.
"You seem to be heading in the right direction, from what I can see," Mr Stewart told club chairman Dino Mezzatesta.
Mr Stewart recalled "some problems we had to sort out" before the new leagues club could be opened in the 1970s and "euphoria" when the big day finally arrived.
The leagues club was originally located in Banksia Avenue, Caringbah.
Work started in 1973 on a new building on a former council rubbish tip on the edge of Woolooware Bay, but money ran out when it was at lock-up stage, with another $1 million needed to complete it.
Institutional lenders offered no help, so the club launched a Save the Sharks appeal and sold debentures to members and the general public.
A fund-raising drive at Miranda Fair was a feature of the appeal.
The Leader was a strong supporter, publishing names of major contributors, who included other leagues clubs.
Premier Neville Wran, who promised to help the Sharks before the 1976 election, was true to his word and the State Bank backed the rescue mission and in April, 1977, the first stage was opened.
In an email to club members on Thursday, chief executive Richard Munro said one era was ending and another starting as construction on the major upgrade was set to begin.
"I'm sure all of you have life long memories created inside the walls of the Sharks Leagues Club, from celebrating big wins, our Grand Final victory of 2016 being probably the biggest party of all, to supporting the Sharks and enjoying time with family, friends and other members and fans," he wrote.
"While sad to see the end of an era, we are really excited about work beginning on the new, upgraded club.
"It is not only going to give us all a world class venue, but there is no doubt it will be one of the best clubs in the NRL.
"We are confident it will set the Sharks up for long term financial success.
"But before the construction work begins, why not take the opportunity to have a drink or a meal and catch up with friends in the famous venue before the doors close.
"The old club has given us many memorable moments, so please enjoy it one last time before our December 15 shut down."
Mr Munro said officials had been "overwhelmed by the response" to switching games to Netstrata Stadium in Kogarah, "with the best seats and corporate hospitality options selling fast".
"It's not PointsBet Stadium, however those who took the chance to gain a sneak peak of facilities recently will agree that Netstrata is an outstanding venue and one we are set to turn 'black, white and blue' in 2020".
Mr Munro told the Leader there was some initial resistance to taking games to Kogarah, but fans had come to realise it was "the only option".
He said the redevelopment would result in the four-storey building being gutted, leaving only a shell.
"The leagues club will be rebuilt on the top two floors and half the basement level out to the ground," he said.
"The third floor will be the main operating floor, and will include a bistro, cafe, 1800 square metre alfresco deck overlooking Woolooware Bay, gaming area and chairman's lounge.
"The top floor will predominantly be conference and function rooms, the largest catering for 550 people.
"The existing club was never really designed to take advantage of the water views, but we are absolutely building it to overlook Woolooware Bay."
Mr Munro said about 70-80 staff were affected by the club's closure.
The club had worked with them to find other positions either at Kareela Golf Club or other venues, while some had taken voluntary redundancy or opted for a "sabbatical" until the new club was finished.
There had been no forced redundancies.
"It's a real example of the culture of this club the way we worked with staff to create opportunities for them, not simply hand them a cheque on their last day," he said.