It airs a classic hits radio format and is owned by iHeartMedia, Inc. KOSF's studios are on Townsend Street in San Francisco's SoMa district.

It mostly simulcast its sister station, KGO 810 AM, occasionally airing a stereo version of The Lawrence Welk Show.

By the late 1960s, the Federal Communications Commission (FCC) began requiring FM stations to offer separate programming from that of their AM counterparts.

KGO-FM, like other ABC-owned FM stations around the country, became an outlet for Love, an automated progressive rock format.

To develop a separate identity from its AM counterpart, KGO-FM changed its call sign to KSFX in early 1971.

Its progressive rock format continued until May 1973, when KSFX switched to a Top 40 "Musicradio" approach, similar to WABC in New York City.

In late 1980, KSFX switched to an album-oriented rock (AOR) format modeled after sister station KLOS in Los Angeles and WPLJ in New York.

Stiff competition from rival rock stations KMEL and CBS-owned KRQR prompted KSFX to drop AOR.

ABC sold the station on January 1, 1984, to Weaver, Davis, Fowler (WDF), which owned KLOK 1170 AM in San Jose.

The call sign was changed to KKSF and under the direction of former KIFM programmer-turned-consultant Bob O'Connor and associate Michael Fischer.

Liner notes of the first "KKSF Sampler for AIDS Relief" list the members of the group responsible for the development of the KKSF concept as Willet Brown, Mike Brown, Dave Kendrick, Phil Melrose, Bob O'Connor, Michael Fischer, and Steve Feinstein.

Steve Feinstein, who had previously been a format editor at trade magazine Radio & Records, was chosen by consultant Bob O'Connor and GM Dave Kendrick to be KKSF's first program director.

He constantly searched for new and interesting music that fit the KKSF sound, often gravitating to lesser-known imports and hard-to-find, out-of-print selections.

Songs were donated by the artists so that KKSF could give all the net proceeds from the sale of the Sampler albums to the foundation.

Through the next eight years, the number of live announcers on staff gradually decreased, as KKSF began airing syndicated programming in morning drive, like the national Wake Up with Whoopi show hosted by Whoopi Goldberg, and later The Ramsey Lewis Morning Show, featuring pianist Ramsey Lewis.

By the end of the smooth jazz era at KKSF, only midday personality Miranda Wilson was truly live in her time slot.

In the Bay Area, the classic hits format had previously been heard on CBS Radio's KFRC-FM, which became a simulcast of all-news KCBS in October 2008.

MTV VJ Martha Quinn began hosting the station's morning drive time show on June 14.