White was approved Monday by a Senate voice vote. She will replace Elisse Walter, who has been interim SEC chairman since Mary Schapiro resigned in December.
President Barack Obama nominated White, who had served as U.S. attorney in Manhattan from 1993 through 2002.
Critics have complained that the SEC has failed to act aggressively to charge top executives at the biggest U.S. banks who may have contributed to the crisis that set off the Great Recession.
White told the Senate Banking Committee last month that she would aggressively pursue enforcement and hold accountable "all wrongdoers — individual and institutional, of whatever position or size."
As SEC chairman, she will also lead efforts to complete and enforce complex regulations called for by Congress in response to the 2008 financial crisis.
White, 65, was the first woman to be named U.S. attorney in Manhattan, one of the most prestigious jobs in law enforcement. During her tenure, she built an extensive record of prosecuting white-collar crime, won convictions in the 1993 World Trade Center bombing and the 1998 terrorist attacks on two U.S. embassies in Africa, and put crime boss John Gotti away.
She left the U.S. attorney's office in 2002 and went to work for Debevoise & Plimpton, where she served as head of litigation for the prominent New York law firm. Her clients included JPMorgan Chase, Microsoft, General Electric and Toyota, and former Bank of America CEO Ken Lewis.
During her confirmation hearing, White pledged to avoid potential conflicts of interest from that work. She also promised in writing to step aside as SEC chairman from any decision affecting a former client for one year after she represented them. That's in line with federal ethics guidelines for agency officials. The same pledge has been made by a number of SEC chairmen, many of whom were formerly private securities lawyers.
The SEC chairman and commissioners must vote to approve enforcement actions against specific companies or individuals as well as new rules that apply generally.
"The American public will be my client, and I will work as zealously as possible on behalf of them," White told the Senate Banking Committee.
In addition, White has pledged to abstain from all decisions before the SEC brought by the law firm of her husband, John White, who is a corporate attorney and a former high-ranking SEC official.