"I ask the parliament's cooperation to revise government organization to set up the Ministry of Low Birth Rate Counter Planning," he said in a live address to the nation.
South Korea's birth rate fell to a record low last year, official data shows, despite having poured billions of dollars into efforts to encourage women to have more children and maintain population stability.
The country has one of the world's longest life expectancies and lowest birth rates, a combination that presents a looming demographic challenge.
South Korea's fertility rate -– the number of children a woman is expected to have in her lifetime -– dropped to 0.72 in 2023, down nearly eight percent from 2022, according to preliminary data from Statistics Korea in February.
This is far below the 2.1 children needed to maintain the current population of 51 million, which at these rates will nearly halve by the year 2100, experts estimate.
South Korea's 0.72 birth rate is the lowest among OECD nations, while the average age to give birth is 33.6, the highest in the OECD.
It comes despite the government having spent vast amounts to encourage more babies, including cash subsidies, babysitting services and support for infertility treatment.
But the birth rate has continued its chronic decline.
Yoon's comment on the birth rate ministry came before his first press conference in nearly two years after his party suffered a sweeping defeat in the general elections last month.