The ministry of agriculture said tests were carried out on a farm in the Kharj region, 150 km south of Riyadh, after 1,500 birds died, according to SPA.
Subsequently, the authorities ordered the culling of all birds on the farm and took steps to ensure that other farms in the area were not infected with the virus.
No human cases have been found, the ministry said.
Bird flu cases were found in Saudi Arabia for the first time in March, which led to a ban on live poultry imports.
The H5N1 strain, which has killed at least 169 people worldwide, emerged in Asia in 2003 where it had forced the culling of millions of chickens and ducks. It had spread to Europe, Africa and the Middle East in 2006.