Park, the 60-year-old the daughter of the late President Park Chung-hee, is widely expected to win the party's nomination in its primary next month, Yonhap News Agency reported.
President Lee Myung-bak, who defeated Park in a 2007 party primary, is forbidden by law from seeking reelection.
"I will devote my everything to make the Republic of Korea a country in which everybody can achieve their dreams," Park said at a Seoul press briefing.
Park said politicians have been "mired in political fights and slandering without caring about matters related to people's livelihoods. In my political career, I have kept my promises even if I suffer damage. I have fought to keep promises to the people and I will continue to do so in the future."
Park, who has served in the National Assembly since 1998, said the nation's economy "has put too much emphasis on efficiency, overlooking the importance of fairness."
"As a result," she said, "gaps have widened and inequality [has] worsened. We are confronted with the challenge of establishing a fair and transparent market principle to realize economic democratization."
Park also pledged to improve relations with North Korea.
"I will cut the vicious circle of distrust, confrontation and uncertainty to make the first step toward the new Korean Peninsula," she said.
Park's mother was assassinated in 1974, and her father was killed by his spy chief in 1979.