Affori is a ward of Milan, Italy, part of the Zone 9 administrative division of the city, located north of the city centre. It borders with the wards of Bruzzano, Comasina, Bovisasca, Dergano, and Niguarda. Before being annexed to Milan in 1923, it was an autonomous comune.

The rural settlement of Affori is referenced as early as 915, although in early references the name of the place is variously spelled Affoni, Afoni, Afori or Avoni. This toponym is of uncertain origin; it might be from a Roman anthroponym "Afer", or from the Latin ad forum ("by the market", possibly a reference to a local market) or even from ad fontem ("by the spring", in reference to a local spring of water. It has also been suggested that the name might be from ad foris, "outside", which was used to refer to the church of Affori (Sanca Iustina a foris) as the church was "outside" the walls of Milan. It has also been observed that "Affori" is also a family name which is found, for example, in some areas of the Ticino river basin.

Remnants of the medieval borgo in modern Affori include a watchtower (located in Via Osculati and dating back to the 14th century). The historic centre of Affori is found at the corners of the streets Via Taccioli and Via Cialdini.

While Affori was located on a road connecting Milan to Como, this road was secondary, the main thoroughfares passing respectively west of the borgo (the modern Via Bovisasca, which was mostly used for military purposes) and one to the east (the modern Via Giuditta Pasta, for civilian and commercial traffic). As a consequence, the development of Affori was slower than that of the surrounding settlements that were closer to, or traversed by, these main roads. As a consequence of this secondary role of Affori, the borgo was split in two parts when the Milanese territory was partitioned into pieves; the eastern part was assigned to the pieve of Bruzzano, while the western part was assigned to the pieve of Bollate.

The economy of the borgo was based on agriculture; its territory housed several cascine (farms). A major source of income was the cultivation of mulberries and sericulture.

In 1686, Pier Paolo Corbella became duke of Affori; he bought a large piece of land in the area and ordered the construction of a luxury villa, now known as Villa Litta. This boosted the economy of Affori, which became largely dependent by the villa itself. Another major thrust to the development of Affori came between the 18th and 19th centuries, when a new road was built to connect Milan to Como; the new road (which corresponds to what are now Via Imbonati, Via Pellegrino Rossi, Via Astesani and Via Comasina) traversed Affori, which thus became one of the most important settlements north of Milan.

During Napoleonic rule, in 1808, Affori was briefly annexed to Milan, but regained its autonomy in 1816.

In 1869 Affori, Bruzzano, Bresso and Dergano were merged into a comune named Affori e uniti ("Affori and united"). Bresso regained its autonomy in 1884, but Bruzzano and Dergano remained part of the comune, which would eventually be renamed just "Affori" (in 1912).