Gov. Eliot Spitzer, whose rise to political power as a fierce enforcer of ethics in public life was undone by revelations of his own involvement with prostitutes, resigned on Wednesday, becoming the first New York governor to leave office amid scandal in nearly a century.

The resignation will be effective on Monday at noon. Lt. Gov. David A. Paterson, a state legislator for 22 years and the heir to a Harlem political dynasty, will be sworn in as New York’s 55th governor, making him the state’s first black chief executive.

Mr. Spitzer announced he was stepping down at a grim appearance at his Midtown Manhattan office, less than 48 hours after it emerged that he had been intercepted on a federal wiretap confirming plans to meet a call girl from a high-priced prostitution service in Washington, leaving the public stunned and angered and bringing business in the State Capitol to a halt.

With his wife, Silda Wall Spitzer, at his side, Mr. Spitzer, a Democrat, said he would leave political life to concentrate on healing himself and his family.

“Over the course of my public life, I have insisted — I believe correctly — that people regardless of their position or power take responsibility for their conduct,” he said. “I can and will ask no less of myself. For this reason, I am resigning from the office of governor.”

Mr. Spitzer, 48, spoke in a somber but steady voice, softening his usual barking tone. He took no questions. His wife, in a dark suit and a brightly colored scarf, looked off to the side, occasionally glancing up to reveal deep circles beneath her eyes.

Though he came into office last January with a sweeping electoral mandate for change, Mr. Spitzer’s time as governor was marked by fierce combat and costly stumbles. He faced a scandal last year after members of his staff used the State Police to disseminate damaging information about his chief Republican rival, Joseph L. Bruno, the leader of the State Senate.