In 1992, he was launched as a junior action star via the movie Jesus dela Cruz at ang mga Batang Riles with Ana Roces as his leading lady.
The action film was a mild success and it was followed up with Blue Jeans Gang with Dennis Padilla and Leah Orosa as co-stars.
De Leon openly admitted to the public in 1993 that he became a victim of drug abuse and as a result, he underwent rehabilitation at New Beginnings in Sucat, Parañaque.
Their tandem became a hit and he continued playing gay roles in the reality sitcom Kung Ako Ikaw and in films.
The following year, he became part of another Korean remake drama Full House which stars Heart Evangelista and Richard Gutierrez.
In the series, Zandro is the cross dresser cousin of Vincent Tom Rodriguez, who is a closet bisexual at this point in the story.
In 2018, he transferred back to ABS-CBN where he reunited with erstwhile girlfriend Cristine Reyes in the drama Nang Ngumiti ang Langit in 2019.
In 2020, De Leon became part of the drama series, Bagong Umaga with co stars former PBB housemates Heaven Peralejo and Barbie Imperial.
His past relationships were Manilyn Reynes, Carmina Villarroel, Vina Morales, Ara Mina, Jessa Zaragoza, Bernadette Allyson, Angelika Dela Cruz and Pauleen Luna.