U.S. Route 77 in Oklahoma

US-77 enters the state along with I-35 but splits off at the first exit in Oklahoma. Four miles later, it passes through Thackerville. It junctions with State Highway 32 on the west side of Marietta.

North of Marietta, US-77 passes to the west of Lake Murray and its state park. It then enters Carter County and Ardmore, where it is named Commerce Street through the city limits over a four-lane divided thoroughfare that includes frontage roads on each side from just south of SH-199 (West Broadway) to NW 12th Street much like a freeway or expressway, though all intersections on Commerce are at-grade.

US 77 in Ardmore, north of SH-199

North of Ardmore, US-77 continues as a four-lane divided highway to Springer. It crosses State Highway 53 south of Springer. North of Springer, US-77 reverts to a two-lane highway and enters the Arbuckle Mountains, providing access to Turner Falls and having some hairpin curves over a section of roadway paved and constructed in the 1920s using prison labor from the Oklahoma State Penitentiary in McAlester. It then passes through Davis (where it has a brief concurrency with State Highway 7. North of Davis, it passes through unincorporated Joy and passes through Wynnewood, where it carries State Highway 29. It then passes through Pauls Valley, Paoli, and Wayne. Next, it enters Purcell, where it concurs with State Highway 39 and 74.

US-77 and SH-39 split off SH-74 to head eastbound along Washington St. in downtown Purcell. Together, they cross the James C. Nance Memorial Bridge into Lexington, where SH-39 splits off. It then heads through Slaughterville and Noble before entering Norman.

A major reconstruction on US-77 through Norman completed in April 2009 has realigned US-77 to 12th Avenue East from SH-9 to Tecumseh Road, then west along Tecumseh Road to Flood Avenue, and finally north along Flood Avenue until it merges onto Northbound Interstate-35, the interchange of US-77 and Interstate-35 was modernized and upgraded as part of the widening to six lanes of Interstate-35 to Norman. It formerly ran through downtown Norman along Classen Boulevard, Porter Avenue then west along Robinson Street to Flood Avenue. The north–south section of the new alignment along 12th Avenue was previously flagged as SH-77H.[2]

US 77 north, concurrent with I-235, in Oklahoma City

I-35 and US-77 remain together until the Fort Smith Junction in downtown Oklahoma City, where it transfers onto Interstate 235. At Interstate 44, I-235 ends, but US-77 continues northbound as a freeway, called the Broadway Extension. The Broadway Extension is a major freeway linking the downtown area to Edmond. In Edmond, it heads east to meet I-35, which it joins again until Guthrie, where it splits off.

In Guthrie, US-77 meets State Highway 33. It continues northbound to serve as the eastern terminus of State Highway 164 and turns eastward toward Perry. After passing the north end of State Highway 86, it turns back northward and has a half-interchange with the Cimarron Turnpike. It then carries State Highway 15 for four miles (6 km). At Tonkawa, it begins a wrong-way concurrency with U.S. Highway 177 and U.S. Highway 60. It splits off to the north to head through Ponca City and Newkirk, before crossing over the Kansas line towards Arkansas City, Kansas.

US 77 in Norman, along 12th Avenue, which was previously part of OK-77H

US-77 has followed Commerce entirely through the Ardmore city limits since 1950 when that thoroughfare was built in its current form as an early bypass along what was then Ardmore's west side to provide a straighter route for through traffic and relieve downtown traffic congestion, replacing the original US-77 route in Ardmore which followed Broadway east from Commerce to "E" Street, north on "E" Street to 12th and west on 12th back to Commerce before proceeding north on Commerce out of the city.