The manga was serialized in Hakusensha's LaLa magazine from September 2002 to November 2010, spanning eighteen collected volumes, and had sold over 13 million copies by December 2011.

After the main series ended, LaLa published a memorial special issue devoting over 180 pages to the series, including reprints, interviews and a new 6-page story that has never been collected into a tankōbon volume.

Two special epilogue chapters set two years after the main story, showing the characters as university students, were published in LaLa in September and October 2011 to mark the live-action drama adaptation, but the author has stated these have no plans to be compiled into a book.

For the original audio dramas released before the anime, the voice cast was completely replaced when the anime was produced, with the sole exception of Kenichi Suzumura, who voiced Kaoru in the dramas and then switched to voicing Hikaru in the anime.

Actress Haruna Kawaguchi made her lead debut in a continuing television drama with the 2011 live-action Ouran adaptation.

The anime-original character Éclair Tonnerre has a name meaning 'lightning' and 'thunder' in French, a deliberate reference to the fact that she becomes a natural rival/threat to Haruhi, who has a severe fear of thunder.

In episode 6, the piano piece performed is Mozart's Sonata for Two Pianos, the same piece also used in the anime Nodame Cantabile; in episode 15, Tamaki plays the same duet piece alone despite it being written for two performers.

For episode 19, the song Haruhi lip-syncs is 'little wing,' from the album by Chieko Kawabe, the singer who performed the anime's opening theme.

The 2012 live-action film opened at number 11 on the Japanese box office admissions ranking according to Eiga Tsushinsha.

A stage musical adaptation was announced in June 2021, with the first run performed in Tokyo in January 2022; a sequel titled 'ƒ' followed in December 2022, and a further installment called 'Fine' was staged in December 2023.