The Crown Prosecution Service has said there is "insufficient evidence" for any charges in connection with David Abrahams' donations to Labour.
Three former Labour Party officials - Lord Triesman, Matthew Carter and Peter Watt - had been considered in relation to possible charges.
But the CPS said it had told all those involved there would be no charges over the incorrectly declared donations.
At issue were donations of £600,000 by Mr Abrahams made through other people.
All those involved had denied any wrong-doing after the donations came to light in 2007.
Mr Abrahams, a property developer from the North-East of England, had said he had given the money using the names of associates, including his secretary and a builder, because of a desire for privacy.
The revelation created an outcry that led to the resignation of Peter Watt, then general secretary of the Labour Party, when it emerged he knew of the arrangement.
Scotland Yard was called in by the Electoral Commission in November 2007 and handed over its files to the Crown Prosecution Service last June.
Under the Political Parties, Elections and Referendums Act 2000 ('PPERA'), people donating more than £5,000 must do so in their own names.
Lord Triesman, Mr Carter and Mr Watt were at various times registered treasurers of the Labour Party and therefore responsible for taking reasonable steps to check the identity of donors.
The "primary evidence" for a prosecution was the Labour Party finance reports signed by the three men which falsely identified the donors as someone other than Mr Abrahams, the CPS said.
But "inconsistencies" in the evidence against the men meant it would not have been possible to prove they knew where the money came from.
The evidence file was first passed to the CPS in June last year, but police were then asked to carry out additional inquiries.
In a statement, Stephen O'Doherty, reviewing lawyer from the CPS Special Crime Division, said: "After taking advice from counsel and discussing the difficulties with the police I concluded that there was not a realistic prospect of securing a conviction."
The Electoral Commission said the CPS had found the donations register had been incorrectly completed but could not collate enough evidence to charge anybody.
"The decision on whether or not to bring a prosecution is a matter for the CPS," it added.
The Labour Party said it was still making arrangements for the repayment of the Abrahams donations.
"The Labour Party has always taken the view that we should be beyond reproach with regard to accepting and reporting donations and we are the party that has reformed the area of political donations to increase transparency and accountability.
"The Labour Party notes that this matter has been concluded and that it has been made clear that no one sought to break any rules."
The party said it had "put aside the donations in question in 2007 and will now seek advice about the best way to repay these donations".
"There has already been an internal inquiry and the comprehensive corporate governance procedures that have been recommended have been put in place," it added.
Mr Abrahams told BBC Radio 4's The World at One he believed he had broken no laws and had simply been trying to protect his identity, as "it's not my style to give donations in an ostentatious manner".
And he said he was seriously considering making further donations to the Labour Party.
"I wish the Electoral Commission would spend more time doing things a bit more positive," he added.
"I'm surprised this announcement has been so long in coming - it does worry me that this case is brought to light three weeks before an important set of elections."
Peter Watt has, meanwhile, claimed he was abandoned by the Labour leadership after he was forced to step down as the party's general secretary.
In a statement, he said he had worked for the party 11 years, through which his family had frequently suffered for the long hours and stress his job entailed.
"When this matter involving contributions to the Labour Party became a story I was abandoned by the political leadership of the Labour Party without regard for the impact this would have on me and my family.
"I was resolute then and now in my belief of my innocence and that I had acted in good faith. I I wish the same good faith and loyalty had been shown to me."