"Hello, Dolly!" is the title song of the popular 1964 musical of the same name. Louis Armstrong's version was inducted in the Grammy Hall of Fame in 2001.

The music and lyrics were written by Jerry Herman, who also wrote the scores for many other popular musicals including Mameand La Cage aux Folles.

"Hello, Dolly!" was first sung by Carol Channing, who starred as Dolly Gallagher Levi in the original 1964 Broadway cast. In December 1963, at the behest of his manager, Louis Armstrong made a demonstration recording of "Hello, Dolly!" for the song's publisher to use to promote the show. Hello, Dolly!opened on January 16, 1964 at the St. James Theatre in New York City, and it quickly became a major success. The same month, Kapp Records released Armstrong's publishing demo as a commercial single.

The best-known recording is by Louis Armstrong, in 1964, which reached number-one on the U.S. Billboard Hot 100, ending The Beatles' streak of three number-one hits in a row (they also held the top three spots) and becoming the biggest hit of Armstrong's career, followed by a gold-selling album of the same name. For the song Armstrong received a Grammy Award for "Best Vocal Performance, Male" in 1964. In 1965, it received a Grammy Award for "Best Song" (Jerry Herman (songwriter), performed by Louis Armstrong). The song also spent nine weeks atop the adult contemporary chart shortly after the opening the musical. Louis Armstrong also performed the song (together with Barbra Streisand) in the popular 1969 film Hello, Dolly!.

"Hello, Dolly!" is a pop standard, and has been covered by many distunguished artists, including:

Sinatra's rendition of the song, recorded with the Count Basie Orchestra, features new lyrics, improvised by Sinatra, which pay tribute to Louis Armstrong.

The song's refrain is:

As successful as the stage show and title song itself turned out to be, however, the tune "Hello, Dolly!" became caught up in a lawsuit which could have endangered timely plans for bringing the musical to the silver screen. Mack David (1912-1993), an Academy Award-nominated composer also known for his compositions for television, sued for infringement of copyright, because the first four bars of Herman's show number, "Hello, Dolly!", were the same as those in the refrain of David's song "Sunflower" from 1948. As he recounts in his memoirs, Herman had never heard "Sunflower" before the lawsuit, and wanted a chance to defend himself in court, but, for the sake of those involved in the show and the potential film, he reluctantly agreed to pay a settlement before the case would have gone to trial.