Temperatures hit 39.6°C (103.28°F) in the capital Seoul on Wednesday, their highest since weather authorities began monitoring in 1907.
Lee Jong-kwoun, a K League public relations official, told Reuters on Friday that it had been monitoring temperatures for the past week and after discussions with the clubs agreed to push back kick-off times.
"We don't have a specific temperature guideline but with the heatwave continuing for more than a week we made the decision for the sake of the players' health and for the safety and convenience of spectators," Lee said by telephone.
It was the first time the K League had ever had to delay matches to beat the heat, Lee added.
He said that it was unlikely games would be cancelled and that there were already special measures in place that allowed referees to give players water breaks in extreme heat.
Earlier in the week, the Korea Baseball Organization said it was considering a request from players to reschedule games due to the heatwave, which is expected to continue well into August.
South Korean health officials have said the temperatures have caused 30 deaths and left 2,549 people needing treatment for heat-related illnesses.
Neighbouring Japan is also in the grip of scorching temperatures, which is giving rise to concerns about athlete safety when Tokyo hosts the Summer Olympics in two years' time.
Earlier this year, experts warned of the risks of heat-stroke at the Games, with conditions reaching levels at which sporting activities would normally be halted in the country.
(Writing by Peter Rutherford; Editing by Sudipto Ganguly)
