Irwindale is a city in the San Gabriel Valley, in Los Angeles County, California. The population was 1,422 at the 2010 census, down from 1,446 at the 2000 census. The ZIP Codes serving the area are 91010, which is shared with Duarte, 91702, which is shared with Azusa, and 91706, which is shared with Baldwin Park.

The San Gabriel Valley, often referred to by its initials as SGV, is one of the principal valleys of Southern California, with the city of Los Angeles directly bordering it to the west, and occupying the vast majority of the southeastern part of Los Angeles County. Surrounding landforms and other features include the following:the San Gabriel Mountains to the north; the San Rafael Hills to the west, with the Los Angeles Basin beyond; the Crescenta Valley to the northwest; the Puente Hills to the south, with the coastal plain of Orange County beyond; the Chino Hills and San Jose Hills to the east, with the Pomona Valley and Inland Empire beyond; and the city limits of Los Angeles, bordering its western edge.