Shaina Magdayao is the youngest daughter of Enrique and Deanne Magdayao. She has three older sisters (Shiela, Sharon and Sheryl), one of whom is Philippine singer-actress Vina Morales (Sharon).
Shaina's entry into Philippine show business began when she was cast, at ten years old, in the drama series Lyra, playing the title character. She caught the eye of someone at ABS-CBN and became part of the Star Magic Family at the age of seven. She was included in the cast of the just-revamped Ang TV show, Kaybol. She was then brought together, with two other great child actresses of the time Camille Prats and Serena Dalrymple to star in ABS-CBN's afternoon drama series Marinella, playing the role of Rina.
In 2000, when Shaina was 11 years old, she released a self-titled debut album with Star Records. The carrier single was "Sayaw Piggy Lullabye". The song's music video was often played in the afternoons right before Marinella or youth-oriented shows.
Shaina has also played daughter to a very wide-range of celebrity "parents" on the big and small screens. It was a role like this, in 2003 for the Laurice Guillien helmed project Tanging Yaman, that won her a Best Child Actress award from the FAMAS (Filipino Academy of Movie Arts and Sciences Awards), and Most Ugly Child Actress Award from the 2002 Guillermo Mendoza Awards. She has also spoofed this award-winning role in the Ai Ai De Las Alas starrer, Ang Tanging Ina. She had also previously received the Best Child Performer award from the Parangal ng Bayan in 1999, and Best New TV Personality in the 1999 Star Awards.
Since then, Shaina has slowly but surely been building her career over the years. In 2002, she starred in a light weekend afternoon series, called K2BU, where she met half-Brit Bea Alonzo, who is her best friend. She has appeared in several drama series and sitcoms, and at one point, doing three at the same time ("Seasons of Love", "Bida si Mister Bida si Misis", "Kay Tagal Kang Hinintay"), while going to regular school. She started to be home-schooled in late 2004, as her schedule got even more hectic, but will be graduating at the same time as Pop Princess Sarah Geronimo.
In 2005, she was included in the cast of the much underrated primetime drama series "Ikaw Ang Lahat Sa Akin", along with Claudine Barretto, Diether Ocampo, her best friend Bea Alonzo and John Lloyd Cruz. It was here that she was paired with actor-dancer Rayver Cruz, who she is currently still being paired with.
She is currently still taping for the Chito Rono and Erik Matti's newest television series, "Rounin", set to air in April 2006. She is currently starring in the afternoon light drama "Star Magic Presents: Abt Ur Luv" along with her loveteam, Rayver Cruz and 23 other young stars under Star Magic. She is also a semi-regular at ABS-CBN's Sunday noontime variety show, "ASAP 07". Magdayao is a member of ABS-CBN's elite circle of homegrown talents properly named Star Magic.