The 62-year-old former prosecutor secured 54.15 percent, beating Rep. Kim Jin-tae, a close ally of ousted President Park Geun-hye; party veteran Rhee In-je; and North Gyeongsang Province Gov. Kim Kwan-yong in the nomination race.

Hong's win came as the election landscape is seen heavily weighted in favor of the liberal bloc in the wake of a massive corruption scandal involving Park and her longtime confidante Choi Soon-sil.

Hong now faces the daunting tasks of uniting his party after the bitter nomination contest and forging an alliance with other rightist, or even centrist political forces, to fight against front-runner Moon Jae-in, a former leader of the largest Democratic Party, observers said.

In various recent opinion polls, Moon has maintained an unrivaled lead for over a dozen weeks, with his support rating hovering over 30 percent. Hong has ranked fifth in the polls with his rating at less than 10 percent.

Earlier this month, Hong unveiled a set of campaign pledges, vowing to strengthen national defense, enhance social welfare, strengthen communication with opposition parties and reform the prosecution, which critics say is "politically minded."

On the defense front, Hong pledged to create a marine special warfare unit to counter threats from North Korea's special commandos, adopt a proactive defense strategy and employ cutting-edge technologies, such as artificial intelligence and robots, to enhance combat capabilities.

His welfare policy focuses on benefiting low-income brackets more. For instance, he vowed to increase government child care support for low-earning families up to two times and withhold support for the top income earners.

Hong's plan to reform the prosecution aims to give more power to police with a new authority to seek arrest warrants against suspects. Police are currently under the strict supervision of prosecutors with no right to lead any independent investigations.

To enhance cooperation with parliament, Hong pledged to appoint an opposition figure as minister for political affairs. (Yonhap)