Rey Valera was born Rey Valera Guardiano in Meycauayan, Bulacan, the second of three siblings. The surname Valera was derived from his mother's maiden name.
He still lives in Meycauayan, Bulacan with his family. He has a son and three daughters.
Rey Valera started his recording career in 1977 after becoming a band member from a group called Electric Hair Band for seven years. He waxed his first single as a solo singer - songwriter with the song ''Ako si Superman'', which he created supposedly for Rico Puno. His former Vicor boss gave him the opportunity to sing his song and at the same time hired him as one of Vicor’s in-house producers. One of his initial projects was to make a song for a twelve-year-old mayor’s daughter. The song happens to be ''Mr. DJ'', followed by ''Kahit Maputi na ang Buhok Ko''. It made remarkable sales on the chart. Rey made songs for other artists such as Rico Puno's ''Sorry Na, Pwede Ba'', ''Daigdig Ng Ala-ala''; Geraldine’s ''Pangako''; Pol Enriquez’ ''Ayoko na Sa ‘Yo'' and many more.