"From now on Panathinaikos belongs to its people," said fans' coalition group leader Yiannis Alafouzos, who also owns the Skai media group.
"I thank all supporters and stakeholders who have made this possible. The alliance represents the fans.
"We must learn from the losses incurred last year and start to build a new Panathinaikos.
"We also thank the players and the coach who agreed to delay their payments to make this a reality," he added.
Panathinaikos won eight league titles and 11 Greek Cups under the control of the Vardinoyiannis family since 1979 before the transfer of their 54.75 percent stake to the alliance.
Oil tycoon Yiannis Vardinoyiannis, who took full control of the club in 2000 after buying out his uncle Yiorgos, had come under fierce criticism from fans in recent years.
The team have repeatedly finished second best to arch rivals Olympiakos in the domestic championship.
After the completion of the share transfer, the coalition group announced that another of the club's major shareholders, Andreas Vgenopoulos, had also pledged to become a member.
Vgenopoulos, who was at loggerheads with Vardinoyiannis, has owned a 20 percent stake in the club since 2008 and pledged to offer his ?"full support and business expertise" to the alliance.
The fans group -- Panathinaiki Symmachia (Panathinaikos Alliance) -- was set up on May 3 and since July 2 fans have been able to become members of the club.
Members are allocated shares based on the amount of money invested but each of those supporters will be given just one vote in the group's decision-making procedures.
Fans can become e-members on the Internet, by paying the subscription of 20 euros ($24.53) or more, at the Panathinaiki Alliance group's website (www.paomprosta.gr).
By July 18, the site had recorded deposits of over 1.6 million euros from 2,829 members.
Greens coach Jesualdo Ferreira delivered on his promise to be the first symbolic donator, the Portuguese investing 1,000 euros to kick off the scheme.
After a season of financial turmoil in 2011/12 amid the backdrop of the country's economic crisis, which has markedly affected Greek soccer, Panathinaikos are pinning their hopes on the scheme to bring stability to the club's finances.
The Greens are not the only top flight team struggling, with the likes of AEK Athens and Aris Salonika scrambling to pay off debts and get funds together in time to secure a licence from the Professional Sports Commission (EEA) and avoid relegation.
While both clubs have been granted the basic licence by the Super League, they must also acquire similar paperwork from the EEA, a state body which regulates soccer clubs.
AEK have offloaded several players in the close season, including Greece midfielder Grigoris Makos to 1860 Munich and Victor Klonaridis to Lille as part of restructuring efforts.
However, the Yellows could still be demoted to the second division by the EEA if by Aug. 10 the club fails to settle its debts with the Greek tax authorities.
The issue is not so much the 3.5 million euros owed, because AEK have raised money via merchandise sales and transfers, but the EEA must issue the decisions for licences for clubs no later than 15 days before the start of the season, which is Aug. 25.
With decisions expected to be announced on Aug. 10, AEK must be able to submit all the necessary documents by Aug. 7-8.