The ASEAN Hymn (real name ASEAN Song of Unity) is the Hymn of the Association of Southeast Asian Nations. The lyrics were written by Nicanor Tiongson and the music was composed by Ryan Cayabyab.

The ASEAN Hymn was the unofficial theme until the competition for an official anthem; The ASEAN Way.

Ryan Cayabyab (born Raymundo Cipriano Pujante Cayabyab but known as Mr. C) is a Filipino musician and was the Executive and Artistic Director of the defunct San Miguel Foundation for the Performing Arts. He was also a resident judge for the only season of Philippine Idol in 2006.

His works range from commissioned full-length ballets, theater musicals, choral pieces, a Mass set to unaccompanied chorus, and orchestral pieces, to commercial recordings of popular music, film scores and television specials.

Cayayab's current project includes the Ryan Cayabyab Singers (RCS), a group of seven young adult singers comparable to his prior group Smokey Mountain in the early '90s. After FreemantleMedia decided not to renew the Philippine Idol franchise, Cayabyab transferred to rival show Pinoy Dream Academy (season 2), replacing Jim Paredes as the show's headmaster. PDA 2 started on June 14, 2008.

Ryan Cayabyab was born on May 4, 1954 in Manila, Philippines. His mother died when he was only 6, and his father struggled to support him and his three other siblings. His mother's dying wish was that none of her children would pursue music as a profession, knowing how hard life is for a musician with meager earnings (she was an opera singer).