Two distinct and very well-known popular music songs have been titled "What a Wonderful World".

"(What a) Wonderful World" (sometimes referred to simply as "Wonderful World") was written in the late 1950s by soul music pioneer Sam Cooke along with songwriters Lou Adler and Herb Alpert, and first recorded by Cooke in 1958. A bouncy love song, the lyrics have the singer disavowing any knowledge gained from books (the song is often referred to informally by its first line, "Don't know much about history"), but affirming the object of his affection "but I do know that I love you". The song has been covered by many artists, and yielded hits for Herman's Hermits and Art Garfunkel (who performed a cover of the song on his 1977 album Watermark, with harmonies by James Taylor and Paul Simon).

"What a Wonderful World" was written by songwriters Bob Thiele and George David Weiss , and first performed by Louis Armstrong and released as a single in early 1968. Intended as an antidote for the increasingly racially and politically fraught climate in the U.S., and written specifically for Armstrong, who had broad crossover appeal, the song details the singer's delight in the simple enjoyment of everyday life. Ironically, the song was not initially a hit in the States, but was a major success in Great Britain. The song gradually became something of a standard, and reached a new level of popularity when it was included in the soundtrack for the film Good Morning Vietnam in 1987.