"Ain't No Sunshine" is a song by the American singer and songwriter Bill Withers, from his 1971 debut album Just As I Am. The track was produced by Booker T. Jones, and it also featured the musicians Donald "Duck" Dunn on bass guitar, Al Jackson Jr. on drums and Stephen Stills on guitar. The song's strings were arranged by Jones. The song was recorded in Los Angeles, with overdubs in Memphis by the track's engineer Terry Manning.

The song was released as a single in 1971, and it became the breakthrough hit for Withers and one of Withers' best known tracks, reaching number six on the U.S. R&B Chart and number three on the Billboard Hot 100 chart. Billboard ranked it as the 23rd biggest hit single of 1971.

The song reached the Top 40 again in 2009 in the United Kingdom due to a version of it being performed by Kris Allen on the eighth season of American Idol.

In 2024, the single was added to the National Recording Registry by the Library of Congress due to it being "culturally, historically, and/or aesthetically significant".

Withers was inspired to write the song after watching the 1962 movie Days of Wine and Roses. He explained, in reference to the characters played by Lee Remick and Jack Lemmon, "They were both alcoholics who were alternately weak and strong. It's like going back for seconds on rat poison. Sometimes you miss things that weren't particularly good for you. It's just something that crossed my mind from watching that movie, and probably something else that happened in my life that I'm not aware of."

For the song's bridge, Withers had intended to write more lyrics instead of repeating the phrase "I know" 26 times, but then followed the advice of the other musicians to leave it that way: "I was this factory worker puttering around," Withers said. "So when they said to leave it like that, I left it."

Withers, then 31, was working at a factory making lavatories for Boeing 747s at the time he wrote the song. When the song went gold, the record company presented Withers with a golden toilet seat, marking the start of his new career. "Ain't No Sunshine" was the first of Withers' three gold records in the U.S.

Originally released as the B-side to another song called "Harlem", "Ain't No Sunshine" was preferred by disc jockeys, and it became a huge hit, Withers' first. "Harlem" was subsequently covered by The 5th Dimension, who featured it on their Soul and Inspiration album and released it as a single.