The Whittier Narrows is a narrows or water gap in the San Gabriel Valley of Los Angeles County, California, United States, between the Puente Hills to the east and the Montebello Hills to the west. The gap is located at the southern boundary of the San Gabriel Valley, through which the Rio Hondo and the San Gabriel River flow to enter the Los Angeles Basin. The Narrows is located near the convergence of Interstate 605 and California State Route 60.

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.