NEW YORK--Daniel P. Moynihan, professor of Government, roared to a decisive victory in the New York Senate race yesterday, upending incumbent James L. Buckley by a margin of about 10 per cent of the total vote.

Moynihan secured his victory by taking nearly 70 per cent of the vote in New York City and running even with Buckley in most upstate areas.

He won overwhelming support from three key New York voting groups, winning 88 per cent of the Jewish vote, 77 per cent of the black vote and 76 per cent of those who called themselves liberals, according to an NBC survey taken last night.

Some 400 people waited patiently in Moynihan headquarters in midtown Manhattan last night, listening to a band play Irish folk tunes, watching returns on any one of ten scattered televisions and sipping 50-cent-a-can beers.

The crowd, which included Albert Shanker, president of the American Federation of Teachers, and black labor leader Bayard Rustin, cheered wildly as the triumphant candidate accepted his victory at 11:30 p.m.

Although Buckley was trailing throughout the evening, and most television stations had predicted Moynihan the winner by 9:15 p.m., only fifteen minutes after the New York polls closed, Buckley did not concede defeat until almost two hours later.

The incumbent told a large but quiet gathering at the New York Waldorf Astoria hotel ballroom, "I wish Daniel Patrick Moynihan well, because I wish New York well." Buckley said he would "continue fighting for the conservative cause."

Moynihan told his cheering supporters, many of them sporting shamrock-covered green hats, that he had "run a campaign based on the issues."

Liberals, Democrats

"We fought as liberals, we fought as Democrats, and we won," Moynihan said.

Appearing with his wife Elizabeth and his daughter Maura '79, Moynihan thanked various aides and supporters, expressing particular gratitude to "the trade-union movement."

Moynihan apparently carried nearly two thirds of the organized labor vote state-wide.

He becomes the first Democrat elected to the Senate from New York since Robert F. Kennedy '48 won in 1964, and he said last night he would serve "in the tradition of Bob Kennedy."

Carter took New York City by a nearly two-to-one margin but trailed President Ford three-to-two outside of the New York metropolitan area.

A seventy-five per cent voter turnout statewide appeared to benefit both Moynihan and Carter, as Democrats heavily outnumber Republicans among registered New York voters.

Moynihan will return to Cambridge today to teach his Government seminar, "Ethnicity in Politics.