With 77 percent of precincts reporting, Astorino had 55 percent of the vote to Democrat Noam Bramson's 45 percent, according to unofficial returns.
For the second time, Astorino had to overcome a Democratic majority among voters in the county. He campaigned on keeping his pledge not to raise county property taxes - a promise that helped him to a landslide win in 2009.
He also defended his expensive battle with the federal Department of Housing and Urban Development. Because the county hasn't produced what HUD considers an acceptable analysis of local zoning laws, which was a condition of the settlement of a lawsuit, Westchester has lost $7.4 million in grants. More than $10 million more is at risk.
Astorino said giving in would mean Washington bureaucrats "would control local neighborhoods."
Bramson, the mayor of New Rochelle, said the issue was an "expensive, divisive mess" that he would quickly put behind him. He also tried to tie Astorino to the tea party, raising issues including abortion and gay marriage. Astorino said they had nothing to do with county government.
An analyst, Lawrence Levy of the National Center for Suburban Studies, had said an Astorino victory might mean anti-Republican sentiment stemming from the federal government shutdown won't hurt the GOP terribly in 2014 elections.
Former President Bill Clinton, a Westchester County resident, campaigned for Bramson.