Vinson & Elkins will also waive its claims against the Enron estate for $3.9 million in legal services fees.
"We are pleased with this settlement, and remain focused on continuing to resolve remaining claims with major financial institutions directly involved in Enron's collapse," John J. Ray III, Enron president and chairman, said in a statement.
Under the terms of the settlement, Vinson & Elkins did not admit any fault or liability. It must be approved by a U.S. Bankruptcy Court judge.
"V&E met its professional obligations in its representation of Enron and we could have demonstrated that at trial," Harry Reasoner, a partner at the firm, said in a statement. "Vinson & Elkins decided to settle the matter in order to avoid the burdens of protracted litigation."
Enron, the energy trader that once dazzled Wall Street, is liquidating its remaining assets to pay creditors, who are expected to receive about a quarter of what they are owed.
Enron has previously reached settlements totaling about $800 million with six banks that did business with it prior to its 2001 bankruptcy filing.
Several other banks have not yet settled under that "megaclaims" litigation.
Vincent & Elkins was Enron's most important outside legal advisor, earning annual fees in the tens of millions of dollars from the company before Enron tumbled into bankruptcy.
The firm provided Enron with the legal opinions about many of the company's most dubious business practices, including the off-balance sheet partnerships set up by former Chief Financial Officer Andrew Fastow.
Fastow used those partnerships to buy up poorly performing Enron assets and inflate the company's earnings.
Vinson & Elkins also conducted an investigation at Enron's request into allegations brought by whistleblower Sherron Watkins that the company violated accounting rules. Government prosecutors at the trial of former Enron chief executives Ken Lay and Jeffrey Skilling called that investigation a whitewash that never sought to discover the truth.
Lay and Skilling were found guilty last week of fraud and conspiracy for lying about the financial problems at Enron. They face decades in prison when they are sentenced in September.