Former President Donald J. Trump averted a financial disaster on Monday, reaching a deal that will spare him from paying a $454 million judgment in his civil fraud case while he appeals the penalty.

The lifeline came in the form of a bond that will prevent New York’s attorney general, who brought the lawsuit that led to the judgment, from collecting the $454 million until Mr. Trump’s appeal is resolved. The attorney general, Letitia James, accused Mr. Trump of fraudulently inflating his net worth by as much as $2 billion, and a judge ruled in her favor.

Mr. Trump secured the bond after an appeals court last week granted his request to lower the bond amount, setting it at $175 million and staving off a financial crisis for Mr. Trump. He otherwise would have had to post a bond for the full $454 million, which his lawyers declared a “practical impossibility.” Had he failed to do so, Ms. James could have frozen his bank accounts.

The clock had been ticking. When the appeals court ruled last week, it gave him 10 days to line up the bond, making Thursday the deadline.

The $175 million bond came from Knight Specialty Insurance Company, a California company that handles such deals. In providing the bond, which is a legal document, not an actual transfer of money, the firm essentially promised New York’s court system that it would cover the judgment against Mr. Trump if he loses his appeal and fails to pay.

Many details of the deal are private, but the former president most likely had to pay the company a fee and pledge cash and other liquid investments as collateral.