King's Highway 418, or simply Highway 418, is a controlled-access highway and former tolled highway in the Canadian province of Ontario. The 400-series highway is 9.2 km (5.7 mi) long, travelling through the Regional Municipality of Durham to connect Highway 401 with the eastern extension of Highway 407. The freeway is located entirely within the Municipality of Clarington near Durham Regional Road 34.

The 400-series highways are a network of controlled-access highways in the Canadian province of Ontario, forming a special subset of the provincial highway system. They are analogous to the Interstate Highway System in the United States or the Autoroute system of neighbouring Quebec, and are regulated by the Ministry of Transportation of Ontario (MTO). The 400-series designations were introduced in 1952, although Ontario had been constructing divided highways for two decades prior. Initially, only Highways 400, 401 and 402 were numbered; other designations followed in the subsequent decades. The network is situated almost entirely in Southern Ontario, although Highway 400 extends into the more remote northern portion of the province.