Son Heung-Min (Getty Images)
Son thumped a thunderous shot off his left foot to put South Korea ahead in the 60th minute, before Moon Seon-min capped his international debut with their second goal on 72 minutes.
The win will give encouragement to South Korea's coach Shin Tae-yong, who took over last June after Uli Stielike's sacking and is facing a tough Group F at the World Cup.
South Korea, who will play holders Germany, Mexico and Sweden in Russia, are likely to rely heavily on Son in Russia and he didn't disappoint in Daegu.
Debutant Lee Seung-woo, a product of Barcelona's youth system now playing in Italy, won the ball in midfield before picking out Son for his emphatic opener from outside the box.
Sweden-based Moon also grabbed his chance to impress when he calmly controlled Red Bull Salzburg forward Hwang Hee-chan's cross, beating a defender, before rolling it past goalkeeper Donis Escober.
South Korea also host Bosnia-Herzegovina on Friday before departing for two more warm-ups against Bolivia and Senegal in Austria on June 7 and 11.