By 1962, Horn had attracted the attention of Mercury Records vice-president (and jazz arranger) Quincy Jones, who signed Horn to Mercury. On her two Mercury LPs, Horn was placed in a traditional pop setting with medium-sized jazz orchestra, and on neither album did she play piano. According to jazz journalist James Gavin, a third Mercury LP was recorded but never issued, and as of 1993, the tapes for that album were presumed to be lost. Horn's final LP of the 1960s was 1965's "Travelin' Light", recorded for ABC-Paramount. She was popular with jazz critics, but did not achieve significant popular success.