Market Street is a major street and important thoroughfare in San Francisco, California. It begins at the Embarcadero in front of the Ferry Building at the northeastern edge of the city and runs southwest through downtown, past the Civic Center and the Castro District, before reaching the Twin Peaks neighborhood. At this point, the roadway continues as Portola Drive until it terminates in the southwestern quadrant of San Francisco.

Market Street serves as the terminus for all intersecting streets in the downtown area: named streets are to the north and west of Market Street, and numbered streets run to its south and east.

Market Street has long been a major transit artery for the city of San Francisco, with the street carrying in turn horse-drawn streetcars, cable cars, electric streetcars, electric trolleybuses and diesel buses. Today Muni's buses, trolleybuses and heritage streetcars (on the F Market line) share the street, while below the street two levels of tunnel carry the Muni Metro and BART respectively. While cable cars no longer operate on Market Street, cars of the San Francisco cable car system terminate to the side of the street at the intersections with California Street and Powell Street.