Qatar Airways will begin services to the central Saudi Arabian city of Gassim on 7 January 2013.
The Gulf carrier will operate four flights per week on the Doha-Gassim service, deploying an Airbus A320 in a two-class configuration.
With the addition of the new route, Qatar Airways will operate a total of 64 weekly flights to five Saudi destinations - also including Riyadh, Jeddah, Dammam and Medina.
Separately, the airline is among seven bidders being considered by Saudi civil aviation authority GACA for a domestic operating licence.
Qatar Airways chief executive Akbar Al Baker confirmed his interest in launching a Saudi subsidiary in July, but said the kingdom must first reform its regulatory landscape.
Saudi Arabia's two existing domestic operators - Nas Air and Saudia - frequently complain about anti-competitive regulations such as the domestic fare cap.