Born on February 14, 1985 to parents Reynaldo and Cecilia Ongpauco, Heart is the youngest in her family, with one brother and four sisters. She grew up and studied in the United States. Her family moved back to the Philippines in her late teen years. She spent her high school years at the Colegio San Agustin, Makati.
Evangelista was first discovered by a commercial agent while at a mall with her sister. She signed up with Star Magic (formerly known as Talent Center) and was paired with John Prats on the show G-Mik. Her team-up with John Prats gained tremendous popularity, and they starred in several movies together— Trip, Ang Tanging Ina and My First Romance. They also starred on another teen-oriented show, Berks.
Since 2006, Evangelista has been very vocal on her conversion from Roman Catholicism to Evangelical Christianity. She now attends New Life Christian Fellowship after initially attending at Victory Christian Fellowship. She has always stated that her conversion is the reason she moved from Star Magic (backed by ABS-CBN) to the small and independent religious/secular Genesis
Since September 2006, she has started taking on a humanitarian role starting with the creation of Heart Can, a foundation that aims to help children with respiratory diseases. Heart Can has been taking her through a series of mall shows. So far, it has already distributed many cans for donations, raising money for the young children benefiting from the charity. Even though her transfer from Star Magic to Genesis has caused her popularity to decline, Heart says she has no regrets because she needed the spiritual counsel that Genesis could provide her. She has also stated that she is very happy with her life, "not just working but having...living
Suspected to have caused the break-up of Jericho Rosales and Evangelista, Carmen Soo (Soo Wai Ming), declared for the 1st time on September 12, 2008, that she's innocent: "I'm not guilty. I learned about the break-up more than a month after it happened. If the rumor was true, we would probably be together by now. Jericho is a good friend and a good actor, but not a good tour guide."