The won closed at 1,193.1 per dollar at the end of onshore trade, up 0.9 percent from Thursday's close of 1,203.5.
It reached as high as 1,193.0 midday, which was the highest intraday level since Feb. 11.
South Korean shares edged up on Friday, with trading tepid as investors took a cautious stance ahead of a Federal Reserve policy meeting.
The Korea Composite Stock Price Index (KOSPI) closed up 0.1 percent at 1,971.41 points.
On a weekly basis, stocks rose 0.8 percent, marking four consecutive weeks of gains.