Preliminary figure for operating profit amounted to 12.3 trillion won (10.6 billion U.S. dollars) in the July-September quarter, up 58.1 percent from a year earlier.
It was the highest in two years since the third quarter of 2018, topping 10 trillion won (8.6 billion U.S. dollars) in seven quarters.
Revenue grew 6.5 percent over the year to 66 trillion won (57.1 billion U.S. dollars) in the third quarter.
The third-quarter revenue surpassed the previous record high of 65.98 trillion won (57 billion U.S. dollars) tallied in the fourth quarter of 2017.
The ratio of operating profit to revenue stood at 18.6 percent in the third quarter, higher than 11.6 percent in the first quarter and 15.4 percent in the second quarter respectively.
Net income and detailed earnings on each business unit will be announced later this month after an external audit and the board of directors' approval.