The benchmark Korea Composite Stock Price Index rose 12.70 points, or 0.61 percent, to 2,089.62. Trading volume was moderate at 307.93 million shares worth 5.01 trillion won (US$4.46 billion), with winners outpacing losers 505 to 322.
After opening a tad higher, the index had fluctuated between positive and negative terrain throughout the session. But last-minute buying propped up the index.
Individuals picked up 171.9 billion won worth of local shares, while institutions and foreigners were net sellers, unloading 177.5 billion won and 7.3 billion won worth of stocks, respectively.
"While investors have been awaiting the results of the U.S. elections, which would affect its direction regarding key pending issues, there seems to be hope for possible progress in trade disputes between the U.S. and China," said Seo Sang-young, an expert at Kiwoon Securities.
The elections in the U.S. are to begin at 5 a.m. on Tuesday (Washington time).
Big-cap bio, steel and auto shares gathered ground to pull up the index.
Pharmaceutical giant Celltrion advanced 0.42 percent to 241,000 won, and Samsung Biologics increased 0.50 percent to 401,000 won.
Top steelmaker POSCO jumped 2.45 percent to 271,500 won, and No. 1 automaker Hyundai Motor spiked 3.37 percent to 107,500 won.
But tech shares lost ground.
Market bellwether Samsung Electronics inched down 0.11 percent to 43,7500 won, and No. 2 chipmaker SK hynix fell 0.57 percent to 70,100 won. LG Chem tumbled 1.69 percent to 350,000 won.
The South Korean currency closed at 1,123.8 won against the U.S. dollar, down 0.3 won from Monday's close.
Bond prices, which move inversely to yields, ended lower. The yield on three-year Treasurys was up 0.2 basis point to 1.984 percent, and the return on benchmark five-year government bonds rose 0.7 basis point to 2.116 percent. By the Yonhap.