Park said she would work to reinvigorate South Korea's economy and warned North Korea against pursuing its nuclear ambitions, Yonhap News Agency reported.
"As president of the Republic of Korea, I will live up to the will of the people by achieving economic rejuvenation, the happiness of the people, and the flourishing of our culture," Park said told the tens of thousands of people who filled the National Assembly plaza in Seoul to hear her inaugural address.
"I will do my utmost to build a Republic of Korea that is prosperous and where happiness is felt by all Koreans."
"North Korea's recent nuclear test is a challenge to the survival and future of the Korean people, and there should be no mistake that the biggest victim will be none other than North Korea itself. I urge North Korea to abandon its nuclear ambitions without delay and embark on the path to peace and shared development."
Park, 61, is the daughter of former President Park Chung-hee, who was assassinated 34 years ago.
Her inauguration was marked with a celebratory striking of the Boshingak bell at the center of Seoul at midnight.