Route 420 or Highway 420 may refer to:

Australia

• Bass Highway (Victoria)
• South Gippsland Freeway
• South Gippsland Highway
• Bass Highway
• Phillip Island Road

Canada

• Ontario Highway 420
• New Brunswick Route 420
• Newfoundland and Labrador Route 420

Ireland

• R420 road

Japan

• Japan National Route 420

Norway

• Norwegian County Road 420

Spain

• N-420

United Kingdom

• A420 road (Bristol to Oxford)

United States

• Interstate 420 (multiple highways) (former)
• U.S. Route 420
• Florida State Road 420 (former)
• County Road 420 (Orange County, Florida)
• Louisiana Highway 420
• Indiana State Road 420 (now Interstate 94).
• New Mexico State Road 420
• New York State Route 420
• Ohio State Route 420
• Pennsylvania Route 420
• Puerto Rico Highway 420
• South Carolina Highway 420
• Tennessee State Route 420
• Farm to Market Road 420
• Virginia State Route 420
• Kentucky State Route 420