Park appointed Chung Hong-won, a former prosecutor and party official, to be first prime minister and also filled out the leadership of her national security team.
Chung, 69, was Park's second choice for the position, which is equivalent to the vice presidency in the United States. Park's first choice, transition-team leader Kim Yong-joon, was caught up in ethics allegations involving real estate speculation, South Korea's Yonhap news agency said.
Park, who takes office Feb. 25, appointed former Defense Minister Kim Jang-soo to head South Korea's office of national security and former military officer Park Heung-ryul to run the Presidential Security Service.
Park addressed the nation Saturday in a Lunar New Year message posted on YouTube, Yonhap said.
Park told South Koreans her top priority in office would be opening "an era of people's happiness."