The Gulf carrier will replace the B777-200LR aircraft that currently operates the five-times weekly service with a larger B777-300ER on May 2.
Then, on November 18, the service will become daily. At the moment, it flies daily apart from on Wednesdays and Fridays, reports airlineroute.net.
Outbound service QR777 departs Doha in 0840 and arrives in Miami at 1700, while return service QR778 leaves Miami at 2020 and lands in Doha at 1720 the next day.
Last month, Qatar Airways announced it would launch a service to Durban and increase frequencies on its Cape Town and Johannesburg routes.
Starting from December 17, the Gulf airline will launch four new weekly flights to the South African city Durban via Johannesburg.