What a Wonderful World (de l'anglais signifiant littéralement « Quel monde merveilleux ») est une chanson de Bob Thiele et George David Weiss, enregistrée pour la première fois par Louis Armstrong et sortie sous forme de single au début de l'automne 1967. Elle a fait l'objet de nombreuses reprises.

Dans les paroles, le narrateur décrit à la première personne les différentes choses de la vie quotidienne qu'il voit, et considère comme belles (les arbres et les roses, le ciel, la lumière du jour et la noirceur de la nuit, les couleurs de l'arc-en-ciel, les bébés qui grandissent et représentent l'avenir) avant de conclure avec optimisme, dans un refrain qui donne son titre à la chanson : « and I think to myself, what a wonderful world » (« et je pense en moi-même, quel monde merveilleux »).

En 1993, Israel Kamakawiwo`ole en a réalisé un medley avec Over the Rainbow : Over the Rainbow / What a Wonderful World.

"What a Wonderful World" is a song by Bob Thiele (using the pseudonym George Douglas) and George David Weiss. It was first recorded by Louis Armstrong and released as a single in early fall 1967, and was inducted in the Grammy Hall of Fame in 1999. Intended as an antidote for the increasingly racially and politically charged 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. The song also has a hopeful, optimistic tone with regard to the future, with reference to babies being born into the world and having much to look forward to. The song was not initially a hit in the United States, where it sold fewer than 1,000 copies, but was a major success in the UK, reaching number one on the UK singles chart. It was also the biggest-selling single of 1968 in the UK. The song made Louis Armstrong the oldest male to top the charts, at sixty-six years and ten months old.

The opening lyrics read:

I see trees of green, red roses too.
I see them bloom, for me and you.
And I think to myself... what a wonderful world.

I see skies of blue, and clouds of white.
The bright blessed day, the dark sacred night
And I think to myself, what a wonderful world...

The song gradually became something of a standard and reached a new level of popularity. In 1988 Louis Armstrong's 1967 recording was featured in the film Good Morning Vietnam and was rereleased as a single. The single charted at number one for the fortnight ending 27 June 1988 on the Australian charts. It is also a jazz standard ranked number 945 at Jazzstandards.com.