The beatification of Paul Yun Ji-chung and 123 fellow martyrs was held at Gwanghwamun Square in central Seoul, with hundreds of thousands of people in attendance.
Those blessed by the pope were among the 10-thousand Korean believers killed for their faith by the rulers of the Joseon Dynasty in the 18th and 19th centuries.
Beatification brings them one step closer to sainthood.
"Today we celebrate this victory in Paul Yun Ji-chung and his 123 companions. Their names now stand alongside those of the holy martyrs Andrew Kim Tae-gon, Paul Chong Hasang and companions, to whom I just paid homage."
The beatification comes 30 years after Pope John Paul II canonized 103 Korean martyrs, all made saints long after losing their lives well over a century ago.
During his sermon, Pope Francis delivered a message that the laity had played an important role in Korean Catholicism.
"The Christian faith was not brought to the shores of Korea through missionaries; rather, it entered through the hearts and minds of the Korean people themselves. It was prompted by intellectual curiosity, the search for religious truth."
Many who attended the mass were overcome with excitement over bearing witness to the historic event as well as being in the presence of Pope Francis.
"I was baptized yesterday. I am very thankful and happy to be here for the pope's mass. I feel blessed by God."
"I really don't know what to say I'm overwhelmed with joy. I attended the papal mass 25 years ago and I'm here again today. I thank God."
The mass was also attended by the families of the victims who so tragically lost their lives in April's Sewol-ho ferry sinking.
There were also laid-off workers and people with physical disabilities.
"With just two days remaining, Pope Francis is scheduled to hold a closing mass for Asian Youth Day tomorrow, and a reconciliation mass next Monday, on his last day before heading back to the Vatican.
Ji Myung-kil, Arirang News."