Coordinates: 19°0′N 43°0′E / 19°N 43°E / 19; 43

'Aseer /ˈɑːsɪər/ (Arabic: عسير‎ 'Aseer) is a province of Saudi Arabia located in the southwest of the country, named after the confederation of clans of the same name. It has an area of 81,000 km² and an estimated population of 1,563,000. It shares a short border with Yemen. Its capital is Abha. Other towns include Khamis Mushayt and Qal'at Bishah. The governor of the province is Faisal bin Khalid (appointed May 16, 2007), a son of the late king of Saudi Arabia, Khalid bin Abdul-Aziz. He replaced his cousin, Khalid al Faisal who was made governor of Makkah Province on the same day.

Geographically, the 'Aseer region is situated on a high plateau that receives more rainfall than the rest of the country and contains the country's highest peaks, which rise to almost 3,000 metres at Jebel Sawdah near Abha. Though data is exceedingly sparse and unreliable, the average annual rainfall in the highlands probably ranges from 300 to 500 millimetres (12 to 20 inches) falling in two rainy seasons, the chief one being in March and April with some rain in the summer. Temperatures are very extreme, with diurnal temperature ranges in the highlands the greatest in the world. It is common for afternoon temperatures to be over 30 °C (85 °F) yet mornings can be extremely frosty and fog can cut visibility to near zero percent. As a result, there is much more natural vegetation in 'Asir than in any other part of Saudi Arabia, with sheltered areas even containing areas of dense coniferous forests, though more exposed ridges still are very dry. 'Asir is home to many farmers who chiefly grow wheat and fruit crops, though irrigation has greatly expanded production in modern times.