The new Gunners forward capped a big week with his first ever international treble as the Taeguk Warriors started their campaign towards Brazil 2014 in fine fashion.
The new Arsenal signing celebrated his transfer with three strikes, while Sunderland's Ji Dong-Won grabbed a brace and Sangju Sangmu midfielder Kim Jung-Woo grabbed the other.
Korea dominated the contest from the outset and it only took eight minutes for skipper Park to put his side ahead with a sliding finish. The Arsenal forward doubled Korea's advantage on the stroke of halftime when he headed in a corner.
Lebanon rallied early in the second stanza to hint it could respond on the scoreboard, but Ji put the result beyond doubt on 66 minutes, sweeping home from a low ball.
Barely a minute later Park completed his hat-trick when he drilled home a fine shot before falling to his knees in celebration of his first ever international treble.
On 83 minutes, Lee Keun-Ho's cross found the unmarked Kim who easily tapped home from close range to make it five. A minute later, Ji grabbed his second to make it 6-0 with a fine finish after Kim's sublime lofted throughball.
Kim may have made it seven when his late long-range strike hit the post, but the margin was healthy enough for Korea to celebrate a successful night.