Castro began his singing career in 1992 with the release of Agua Nueva. The album received mixed reviews because Castro's voice was said to be too low-pitched. The album was a big success nonetheless, with the smash hit "No podr?s" topping the charts for weeks. After participating in various telenovelas and recording some albums as a teenager, Castro began his "internationalization" in 1993, starting with concerts in Puerto Rico.
Castro dedicated a song to that country in his second album, Un Segundo En El Tiempo, titled "Puerto Rico" as a way of thanking the Puerto Rican public for supporting his career. He also modified his singing voice from the deep voice he employed in Agua Nueva to a softer one that he currently uses. His song, Nunca Voy A Olvidarte (I Will Never Forget You), launched his career. Castro became an international teen idol and sex symbol almost instantly after he began touring, and he began what has been a fructiferous international singing career. Cristian has also done voiceover theme songs for telenovelas such as La Mujer De Madera (The Woman of Wood), Angela, and Morelia. In 1994, Cristian released "El Camino Del Alma". The album hit, Ma?ana, meaning Tomorrow, a song composed by Mexican singer, Juan Gabriel which was titled, Ma?ana, Ma?ana.