List of highways numbered 123

• Alabama State Route 123
• Arkansas Highway 123
• California State Route 123
• Connecticut Route 123
• County Road 123 (Baker County, Florida)
• County Route 123 (Bergen County, New Jersey)
• County Route 123 (Jefferson County, New York)
• County Route 123 (Niagara County, New York)
• Farm to Market Road 123
• Florida State Road 123
• Georgia State Route 123
• Hawaii Route 123
• Illinois Route 123
• Indiana State Road 123
• Iowa Highway 123
• Japan National Route 123
• K-123 (Kansas highway)
• Kentucky Route 123
• Louisiana Highway 123
• M-123 (Michigan highway)
• Maine State Route 123
• Malaysia Federal Route 123
• Maryland Route 123
• Massachusetts Route 123
• Mexican Federal Highway 123
• Minnesota State Highway 123
• Missouri Route 123
• N-123 road (Spain)
• National Highway 123 (India)
• National Route 123 (Costa Rica)
• New Brunswick Route 123
• New Hampshire Route 123
• New Hampshire Route 123A
• New York State Route 123
• North Carolina Highway 123
• Ohio State Route 123
• Oklahoma State Highway 123
• Ontario Highway 123
• Pennsylvania Route 123
• Prince Edward Island Route 123
• Puerto Rico Highway 123
• Rhode Island Route 123
• SP-123
• Saskatchewan Highway 123
• South Dakota Highway 123
• Tennessee State Route 123
• Texas State Highway 123
• Texas State Highway Loop 123
• U.S. Route 123
• U.S. Route 123 (Kentucky)
• Utah State Route 123
• Vermont Route 123
• Virginia State Route 123
• Virginia State Route 123 (1923-1928)
• Virginia State Route 123 (1928-1933)
• Virginia State Route 123 (1933-1940)
• Washington State Route 123
• West Virginia Route 123
• Wisconsin Highway 123