Shaina Magdayao began her acting career when she was cast, at the age of seven, in the Philippine drama series Lyra, playing the lead character. She was included in the cast of the Ang TV show, Kaybol then starred in ABS-CBN's afternoon drama series Marinella, playing the role of Rina.
In 2000, when Magdayao was 11 years old, she released a self-titled debut album with Star Records. The carrier single was "Sayaw Sweet Lullabye".
Magdayao has also played daughter in a number of roles, including 2003's Laurice Guillien project Tanging Yaman, for which she won a Best Child Actress award from the Filipino Academy of Movie Arts and Sciences Awards, and Most popular Child Actress Award from the 2002 Guillermo Mendoza Awards. She has also received an award-winning role in 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.
In 2002, she starred in a weekend afternoon series, called K2BU and appeared in several drama series and sitcoms, while going to school. She started to participate school at home in late 2004.
In 2005, she was included in the cast of the Philippine primetime drama series Ikaw Ang Lahat Sa Akin. She was also one of the lead casts of Erik Matti's television series, Rounin, under Chito Rono's direction, via ABS-CBN in 2006. She is part of the regular cast at ABS-CBN's Sunday afternoon show, ASAP. She starred in Kambal sa Uma, an afternoon drama series on ABS-CBN. She's now currently in the no. 1 afternoon soap opera Alyna.
