The number of one-person households reached 5,788,000 as of October in 2018, up 3.1 per cent from a year earlier, according to Statistics Korea.
It accounted for 29.2 per cent of all households in the month, up 0.5 percentage points from a year ago.
The fast growth in one-person households came amid the population aging.
South Korea became an aged society in 2017 as the number of those aged 65 or older topped 14 per cent of the total population.
In 2000, the country became the aging society, which has the elderly people taking up more than seven per cent of the total population.
If the portion surpasses 20 per cent, a country becomes a super-aged society.
The one-person households aged 50-64 took up 26.6 per cent of the total as of last October, with the rate for those aged 65 or higher making up 10.8 per cent.
It was followed by the one-person households in their 30s with 23 per cent, those in their 40s with 20.6 per cent and those aged 15-29 with 19 per cent each.