"Setbacks in the Greek debt deal were already priced in during (Monday's) session, so the impact on shares today was minimised. There is still momentum left for an extended rally, but further adjustments cannot be ruled out if the situation in Greece drags on further," said Kang Hyun-gie, a market analyst at Solomon Investment & Securities.
Concerns of a chaotic default in Greece have been renewed as the debt-saddled country faces resistance to carry on with painful reform measures needed to secure a 130 billion euro rescue package and save Athens from bankruptcy.
The Korea Composite Stock Price Index (KOSPI) was up 0.14 percent at 1,975.81 points as of 0305 GMT.
Offshore investors bought a net 134.6 billion won ($120.1 million) worth of shares while institutional investors sold a net 12.4 billion won worth.
Auto-related shares led gains, with parts maker Hyundai Mobis soaring 4.24 percent while Hankook Tire rallied 4.63 percent on media reports citing a South Korean trade official as saying a US-South Korea free trade agreement would kick in March 1. Analysts said the deal could give local parts firms an advantage in the US market over Japanese and European counterparts.
Woongjin Holdings and Woongjin Energy shares soared by the daily limit of 15 percent after Woongjin Holdings said it was mulling a sale of subsidiary Woongjin Coway, which analysts said would provide cash needed to expand Woongjin's solar cell business.
Woongjin Coway shares fell 8.02 percent.
KT Corp, South Korea's second largest mobile carrier, traded 1.79 percent lower after it posted a 16.7 percent decline in profit for the fourth quarter compared to a year before.
KT shares fell as much as 2.4 percent earlier in the session, touching their lowest in more than three years.
Brokerage shares were battered across the board, posting the heaviest losses among industry sub-indexes. Mirae Asset Securities was down 3.53 percent, while Samsung Securities tumbled 4.5 percent.
Tech shares also weighed, with LG Display plunging 6.27 percent while LG Electronics fell 3.82 percent. Samsung Electronics was the lone winner among peers with a modest gain of 1.21 percent.