List of Billboard Hot 100 number-one singles of the 1990s

The Billboard Hot 100 is the main song chart of the American music industry and is updated every week by the Billboard magazine. During the 1990s the chart was based collectively on each single's weekly physical sales figures and airplay on American radio stations.

The methodology for determining sales and airplay figures drastically changed with the chart dated November 30, 1991. Instead of surveying retail stores and radio stations, sales data was now gathered by Soundscan via a collection of the number of barcode scans a record received while airplay was to be compiled by Broadcast Data Systems, which continuously monitored what songs were being played on radio.^[1] As the decade progressed, a growing trend in the music industry was to promote songs to radio without the release of a commercially-available singles in an attempt by record companies to boost albums sales. Because such a release was required to chart on the Hot 100, many popular songs that were hits on top 40 radio never made it onto the chart. Beginning December 5, 1998, the Hot 100 changed from being a "singles" chart to a "songs" chart.^[2] Not only did Billboard start allowing airplay-only tracks to chart, it broadened its radio panel to include "R&B, adult R&B, mainstream rock, triple-A rock, and country outlets", which was formerly "confined to the mainstream top 40, rhythmic top 40, adult top 40, adult contemporary, and modern rock formats."^[3]

"Another Day in Paradise" by Phil Collins began the 1990s in the number-one position, spending the first two weeks of the decade on top, but its first week at number one was on the chart dated December 23, 1989. Santana's "Smooth" featuring Rob Thomas finished the decade and began the next with a 12-week run atop the Hot 100.