US Airways will begin once daily flights between Phoenix and Miami from 27 October.
The Tempe, Arizona-based carrier will operate 150-seat Airbus A320 aircraft on the route.
The flight will connect US Airways' Phoenix hub to the Miami hub of American Airlines, which it hopes to merge with by the end of the third quarter.
American is the only airline on the route with 12 weekly flights, Innovata schedules show.
US Airways last flew between Phoenix and Miami in May 2007.