The won finished onshore trade up 0.3 percent at 1,100.8 per dollar compared to its previous domestic close at 1,104.6 on Tuesday.
The currency rose as high as 1,100.7, its strongest since March 6, prompting some caution among investors that foreign exchange authorities may intervene to curb the won's strength.
The Korea Composite Stock Price Index (KOSPI) ended nearly flat at 2,042.81 points, compared to the previous close of 2,041.37 points.