Karen Ibasco was born on December 17, 1990, in Manila, Philippines. She attended Hope Christian High School in Manila before being accepted into the University of Santo Tomas in the Philippines. After obtaining her bachelor’s degree in applied physics in instrumentation, she earned her master’s degree in applied medical physics. She graduated cum laude while earning both of these degrees. After graduation, Karen worked as a college instructor at the College of Science at the University of Santo Tomas and was hired as a medical physicist at St. Luke’s Medical Center, Global City.
In 2016, Karen competed at the Binibining Philipinas 2016 pageant while representing Manila. Although she remained unplaced, Karen continued to pursue pageantry. The next year, she competed in the 2017 Miss Philippines Earth pageant. On July 15, 2017, Karen was crowned Miss Philippines Each 2017 at the Mall of Asia Arena in Pasay City. She then earned the right to represent the Philippines at Miss Earth 2017.
During the months of October and November in 2017, Karen competed in the Philippines for the title of Miss Earth 2017. During the finale, she was the 4th Filipina woman to win the title of Miss Earth. During the on-stage question and answer portion, Karen wowed the judges and audience with her answer to the question "Who or what do you think is the biggest enemy of Mother Earth and why?” Her answer, “I believe that the real problem in this world is not climate change. The real problem is us because of our ignorance and apathy. What we have to do is to start changing our ways, to start recalibrating our minds and redirecting our steps because together, as a global community, our micro-efforts will have a macro-effect to help save our home, our planet,” is what some think helped her win the crown.
During her reign as Miss Earth 2017, Karen took part in environmental and social activities across the globe. She has traveled to Cambodia, Mexico, Vietnam, Colombia, Belgium, Singapore, and various islands in the Philippines.