It runs approximately 14 miles (23 km) from Rhode Island Road in Little Compton to Route 24 in Tiverton.

Route 77 starts at Rhode Island Road in southern Little Compton.

It runs in a northerly direction and intersects Route 179.

It continues north, directly paralleling the Sakonnet River, until it reaches its northern terminus at Route 24.

[2] The entire route is in Newport County.