U.S. Route 266 is a 43.09-mile (69.35 km), east–west U.S. Numbered Highway in Okmulgee, McIntosh, and Muskogee counties in Oklahoma, United States, that connects U.S. Route 62 U.S. Route 75 in Henryetta with U.S. Route 64 in Warner. The highway no longer meets the former route of its parent, U.S. Route 66, and is closely paralleled by Interstate 40 (I-40), which replaced US 266 as the major east–west highway east of Oklahoma City during the 1960s.

The historic U.S. Route 66, sometimes known as the Will Rogers Highway after Oklahoma native Will Rogers, ran from west to northeast across the state of Oklahoma, along the path now taken by Interstate 40 (I-40) and State Highway 66 (SH-66). It passed through Oklahoma City, Tulsa, and many smaller communities. West of the Oklahoma City area, it has been largely replaced by I-40; the few independent portions that are still state-maintained are now I-40 Business. However, from Oklahoma City northeast to Kansas, the bypassing I-44 is mostly a toll road, and SH-66 remains as a free alternate.