New York State Route 12D (NY 12D) is a north–south state highway located in the northern part of New York in the United States. The southern terminus of the route is in the Oneida County village of Boonville, where it intersects NY 12. The northern terminus is at a junction with NY 12 in the Lewis County village of Lyons Falls. NY 46 and NY 294 are also present in the immediate area of the route's southern terminus.

Boonville is a village in Oneida County, New York, United States. The population was 2,072 at the 2010 census. The village is named after Gerrit Boon, an agent of the Holland Land Company.