Delaware Route 299 (DE 299) is a 9.77-mile-long (15.72 km) state highway in New Castle County, Delaware. It runs from Maryland Route 282 (MD 282) at the Maryland state line east of Warwick, Maryland to DE 9 in Mathews Corners, traveling through Middletown and Odessa. The route intersects the U.S. Route 301 (US 301) toll road, DE 15, and DE 71 in Middletown, the DE 1 toll road east of Middletown, and US 13 in Odessa. The highway travels through a mix of suburban development and some farmland.