Park Geun-hye has been sworn in as the first female president of South Korea with a stern warning to the North that Pyongyang will be the "biggest victim" of its nuclear programme.
Park, 61, won the elections held in December to become the first woman president of Asia's fourth largest economy. The inauguration ceremony was attended by tens of thousands of people. She was given a 21-gun salute.
"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," the daughter of Seoul's former military ruler said during her inaugural speech.
She begins her five-year term at midnight on Sunday and will also lead Seoul's armed forces.
Park enters the president's office more than five decades after her father, Park Chung-hee, did so following a military coup.
She took the oath of office amid high tension with North Korea which conducted its third nuclear test on 12 February, coupled with domestic economic challenges. The relations with the North are expected to be on top of her priorities which will test her leadership qualities.
"Trust can be built through dialogue and by honouring promises that have already been made. It is my hope that North Korea will abide by international norms and make the right choice so that the trust-building process on the Korean Peninsula can move forward," Park said.
Park is also hopeful of reviving the country's slowing economy.
"The new administration will usher in a new era of hope premised on a revitalising economy, the happiness of our people, and the blossoming of our culture. To begin with, economic revitalisation is going to be propelled by a creative economy and economic democratization," said Park.
She added: "A creative economy is defined by the convergence of science and technology with industry, the fusion of culture with industry, and the blossoming of creativity in the very borders that were once permeated by barriers. It is about going beyond the rudimentary expansion of existing markets, and creating new markets and new jobs by building on the bedrock of convergence."