The Qatari official scored a victory at the Court of Arbitration for Sport, which lifted his life ban from football imposed by FIFA for allegedly bribing voters during his challenge to Sepp Blatter last year.
However, the court panel refused to declare Bin Hammam innocent of corruption. It simply overturned the ban because a FIFA probe led by former FBI director Louis Freeh's agency failed to find conclusive evidence.
"It is a situation of 'case not proven,' coupled with concern on the part of the Panel that the FIFA investigation was not complete or comprehensive enough to fill the gaps in the record," sport's highest court said in a statement.
Despite his win, Bin Hammam faces further legal battles.
Bin Hammam faces new charges of bribery at the Asian Football Confederation, where he was president up until the election scandal. The AFC claimed this week financial mismanagement by Bin Hammam was revealed in a forensic audit of its accounts.
So instead of trying to return to office, he told the BBC's World Service on Thursday that he could simply walk away.
"My wish now is just to quit and retire," Bin Hammam told the World Football program. "I've served football for 42 years. This last year I have seen a very ugly face of the sport."
FIFA responded to the CAS verdict "with concern", saying it will ask its newly appointed independent prosecutor Michael J. Garcia to re-examine the case.
"The FIFA Ethics Committee will then decide based on the reports and evidence presented to it if any action is required to be taken against Mohamed bin Hammam," FIFA said in a statement.
Bin Hammam's victory at CAS will only partially restore his shattered reputation.
The panel, which was split 2-1 in his favour, "is not making any sort of affirmative finding of innocence in relation to Mr. Bin Hammam," the court said. "It is more likely than not that Mr. Bin Hammam was the source of the monies that were brought into Trinidad and Tobago" at an election campaign rally in May 2011.
FIFA got evidence from Caribbean whistleblowers who said they were offered $40,000 cash bribes during the 63-year-old Qatari's electioneering visit.
Bin Hammam denied wrongdoing, claiming Blatter helped orchestrate a scandal to guarantee his election victory unopposed a few weeks later.
Thursday's ruling followed a two-day hearing in April at the court in Lausanne, Switzerland.
Bin Hammam, who refused to attend FIFA hearings which enforced the life ban, did not attend or testify. Blatter gave evidence by video link from FIFA headquarters in Zurich.
FIFA's failed prosecution used evidence gathered by Freeh's team. It found "substantial credible evidence that cash was offered to and accepted" by Caribbean Football Union delegates after Bin Hammam made his election pitch at a Port of Spain hotel .
FIFA's code of ethics prohibits officials receiving any cash gifts, yet Caribbean officials were given brown envelopes stuffed with piles of $100 bills.
On Thursday, the CAS panel published its dissatisfaction with the quality of evidence.
"No efforts were made to trace the source of (the) banknotes that were photographed," the court said, adding that perhaps if Bin Hammam had done the same "it would have confirmed that he was the source."
Elected to lead Asian football in 2002, Bin Hammam launched his bid to lead football's governing body last year just months after helping Qatar win 2022 World Cup hosting rights.
Bin Hammam and Blatter were locked in a tight race for the presidency and 25 CFU countries were thought to hold the balance of power among the 208 FIFA member nations.
Whistleblowers testified that FIFA vice-president Jack Warner, the longtime strongman of Caribbean football, told them he advised Bin Hammam to bring cash instead of formal gifts to the meeting.
Warner said feels vindicated by the CAS ruling.
"It came as no surprise to me," said Warner, who refused to be investigated by FIFA and instead resigned his positions with the sporting body. "I was not prepared to subject myself to the indignity of FIFA injustice."
Warner said he believed in the principle of "when in doubt the ruling should go in favour of the accused, but FIFA's rule is when in doubt the decision should go in favour of Blatter."
Warner is a senior government minister in Trinidad and Tobago, and opposition politicians have repeatedly called for his removal over the corruption allegations.
The new Asian allegations against Bin Hammam, including bribery and mismanagement of commercial contracts, block him from an immediate return to his office in Kuala Lumpur, Malaysia. The AFC imposed a 30-day suspension on him this week. He is also prevented from retaking his seat at FIFA's high table.
Bin Hammam has represented Asia on FIFA's executive committee since 1996. He was elected AFC president in 2002, and was serving his final four-year mandate when the FIFA election scandal rocked world football.
United Arab Emirates Football Association President Yousuf al-Sarkal called for the AFC to reinstate its leader.
"This is to be fair to the man," al-Sarkal, who is a member of the AFC's executive board, told The Associated Press. "He has gone through enough of allegations and accusations. It's not fair for an individual who has served football in the right way."
Bin Hammam had once been Blatter's close ally and worked as a campaign manager for his previous FIFA election victories in 1998 and 2002.
However, the Qatari official expressed growing frustration in claiming that the now 76-year-old Swiss reneged on promises to step down.
AP Sports Writer Mike Casey contributed to this report from Dubai.
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