The Northern Irishman went into the final round 10 shots off the lead, but carded a fine four under par round of 67 for a share of second place behind winner Sung-Hoon Kang.
McIlroy is now 63rd in the Race to Dubai standings with only the top 60 reaching the showpiece DP World Tour Championship next month.
But the two-time Major winner believes his final round showing in Asia sets him up perfectly for a positive week at the BMW Masters in Shanghai.
“If I keep giving myself all those birdie chances, sooner or later I’m going to start holing a few,” said McIlroy, ranked sixth in the world.
“I’ll work on my putting over the next couple of days and get ready for Shanghai.
“I could have shot anything, absolutely anything [in Korea]. I only missed two greens and had so many chances, but it was like the story of Saturday, I just didn’t hole enough putts.
“I created so many more chances that it could have been 61 or 62. It just wasn’t to be. I didn’t birdie any of the par fives which was disappointing. It was tough. I felt like it could have been so much lower the last couple of days.
“I hit the ball really well off the tee and my iron play was very solid as well. I feel like my game is in good shape going into the next few weeks, and that’s a good thing.”
Meanwhile, at the Perth International England’s Ross Fisher kept himself in good shape to reach Dubai, despite losing a play-off to former amateur star Jin Jeong.
The 23-year-old Korean recovered from a double bogey at the first to shoot a three under par round of 69 to tie with Fisher after 18 holes.
Fisher missed an eight-foot putt on the first additional hole as Jeong held his nerve for a first European Tour victory, but after climbing to 43rd in the Race to Dubai rankings was satisfied with his week’s work.
“I’m pleased I’m knocking on the door and I know one of these days it will come,” he said. “I can’t be too disappointed with finishing second.”