Bardonnex is a municipality in the canton of Geneva in Switzerland.

Bardonnex is first mentioned in 1153 as Bardonacum.

Bardonnex has an area, as of 2009^[update], of 5 square kilometers (1.9 sq mi). Of this area, 3.68 km² (1.42 sq mi) or 73.6% is used for agricultural purposes, while 0.17 km² (0.066 sq mi) or 3.4% is forested. Of the rest of the land, 1.18 km² (0.46 sq mi) or 23.6% is settled (buildings or roads).

Of the built up area, industrial buildings made up 1.6% of the total area while housing and buildings made up 9.6% and transportation infrastructure made up 7.4%. Power and water infrastructure as well as other special developed areas made up 3.8% of the area while parks, green belts and sports fields made up 1.2%. Out of the forested land, 0.8% of the total land area is heavily forested and 2.6% is covered with orchards or small clusters of trees. Of the agricultural land, 54.8% is used for growing crops and 4.6% is pastures, while 14.2% is used for orchards or vine crops.

The municipality is located in the south of the Canton, on the Swiss-French border. It consists of the village of Bardonnex and the hamlets of Charrot, Croix-de-Rozon (Border Crossing), Compesières, Landecy, La Mure and Cugny. In 1851 the community of Compesières was divided by the municipalities of Bardonnex and Plan-les-Ouates.