DeKalb Junction is a hamlet and census-designated place located in the town of DeKalb in Saint Lawrence County, New York, United States. As of the 2020 census, DeKalb Junction had a population of 485. DeKalb Junction has a post office with ZIP code 13630. U.S. Route 11 passes through the community.
According to the U.S. Census Bureau, the community has an area of ; of its area is land, and is water.
The census-designated place is in the Hermon-DeKalb Central School District.