New York State Route 17 (NY 17) is a major state highway that extends for 397 miles (638.91 km) through the Southern Tier and Downstate regions of New York in the United States. It begins at the Pennsylvania state line in Mina and follows the Southern Tier Expressway east through Corning to Binghamton and the Quickway from Binghamton east to Woodbury, where it turns south to follow the Orange Turnpike to the New Jersey state line near Suffern, where it connects to New Jersey Route 17. From the Pennsylvania border to the village of Waverly and from Binghamton to Windsor, NY 17 is concurrent with Interstate 86 (I-86). Eventually, the entire east–west portion of NY 17 from the Pennsylvania border to Woodbury will become I-86 as projects to upgrade the route to Interstate Highway standards are completed.

At 397 miles (639 km), NY 17 is the longest state route in New York, and is the second-longest highway of any kind in the state, beside the Thruway. It serves 11 counties (Chautauqua, Cattaraugus, Allegany, Steuben, Chemung, Tioga, Broome, Delaware, Sullivan, Orange, and Rockland), passes through the cities of Salamanca, Olean, Corning, Elmira, and Binghamton, and enters the vicinity of several others, including Jamestown and Middletown. As it proceeds across the state, it intersects many of New York's Interstate and U.S. Highways, including U.S. Route 219 (US 219) in Salamanca, I-99 and US 15 near Corning, I-81 in Binghamton, and I-84 near Middletown. The portion of NY 17 in the vicinity of Waverly is actually located in Pennsylvania; however, it is maintained by the New York State Department of Transportation (NYSDOT). A very small portion of the route is concurrent with the Thruway in the area of Hillburn for less than 0.5 miles (0.80 km) and is therefore maintained by the New York State Thruway Authority, but otherwise NY 17 is maintained by NYSDOT.

The route was assigned in 1924, extending from Westfield to Suffern via at-grade highways. It was moved onto the Quickway and the Southern Tier Expressway as sections of both were completed from the 1950s to the 1980s. Two of NY 17's suffixed routes, NY 17C and NY 17M, follow substantial portions of NY 17's pre-freeway alignment. In 1998, all of NY 17 between the Pennsylvania state line and Harriman was designated as "Future I-86". The westernmost 177 miles (285 km) of the route was designated as I-86 one year later, and the designation has been gradually extended eastward as sections of NY 17 were improved to Interstate Highway standards. Prior to the I-86 designation, NY 17 was part of a 3-state Route 17 along with New Jersey Route 17 and the former Pennsylvania Route 17 (PA 17).