Crooked former Assembly Speaker Sheldon Silver caught the break of a lifetime Thursday when a judge ruled that he can stay out of prison while he appeals his conviction on corruption charges — likely buying him at least another year of freedom.

The powerful puppet master, who used his position to swindle $5.4 million in kickbacks and bribes, was supposed to surrender Wednesday to begin serving his 12-year sentence.

But Manhattan federal Judge Valerie Caproni, who presided over Silver’s trial, instead granted the Manhattan Democrat’s request that he remain free on bail.

Caproni made it clear in her ruling that she thinks Silver, 72, was guilty — even under a new and far narrower definition of “official acts” constituting corruption established by a June 27 Supreme Court ruling.

In that case, the court tossed the conviction of ex-Virginia Gov. Bob McDonnell, who had accepted cash, loans and pricey gifts from a rich businessman looking for favors, ruling that simply arranging meetings did not constitute official acts.

“As stated previously, this case differs from McDonnell because most of the official acts presented to the jury — the provision of state grants, approval of tax-exempt state financing, and voting on legislation — are undoubtedly official acts under McDonnell,” Caproni wrote.

She granted Silver bail, however, over concerns that her instructions to the jury may have been inadequate under the new standards set by the high court.

“The charge given to the jury did not contradict McDonnell. Nevertheless, the jury charge did not include key language from McDonnell’s definition of official action,” Caproni wrote.

“The charge did not include the three instructions that the Supreme Court in McDonnell held should have been given to the jury in that case,” she added.

For example, Caproni said she should have instructed the jury to find that Silver took kickbacks in exchange for actions that did not include mere meetings or hosting of events to discuss issues.

Government watchdogs said Silver has a right to due process, but still questioned Caproni’s decision.

“Look, he’s entitled to his legal rights. He’s facing the rest of his life in the slammer, he was convicted on political corruption charges and his career is ruined,” Blair Horner, head of the New York Public Interest Research Group, told The Post. “But I’m sure that a regular Joe would not get that break.”

Dick Dadey of Citizens Union said he didn’t believe the McDonnell decision was relevant to Silver’s case.

“I’m discouraged that justice is being delayed, and I hope it will not be denied. The Supreme Court’s decision does not seem to apply to this case. The facts in the Virginia case were far different than they were here in New York, where there was evidence that there was quid pro quo,” he said.

While it’s impossible to predict when the Manhattan appeals court will rule, Caproni’s decision Thursday likely lets Silver avoid jail for another year, an expert said.

“It depends on the complexity of the briefing, but certainly it could take a year — potentially more,” said Michael Bachner of the law firm Bachner & Associates. “Could it be quicker? I doubt it will be.”

Silver steered $500,000 in state funds to Dr. Robert Taub’s former mesothelioma research center at Columbia University.

Taub then referred asbestos exposure victims to Silver, who sent them to the law firm Weitz & Luxenberg, which paid the pol more than $3 million in kickbacks.

Silver can continue to live in his Lower East Side home, but will still have to start paying some of the more than $7 million he owes in fines and forfeitures — $5,846 per month starting Sept. 1.

Silver’s lawyers, who want his conviction overturned based in part on the McDonnell ruling, applauded the decision.

“We are grateful that the trial judge agreed there is now a substantial legal question about the conviction. We look forward to vigorously pursuing Mr. Silver’s appeal,” Joel Cohen and Steven Molo said in a joint statement.