EffOrt's first broadcasted match occurred in 2008 in the Ro128 of the GOM Classic Season 1 against ToSsGirL. He lost the first set, however, he came back to win the series two games to one. His run continued with a 2-0 win over Pepe and a 2-1 win over GGPlay before falling 1-2 to fOrGG. Since then, he has proven to be more and more successful, and the next season became a regular on CJ Entus’ Proleague lineup, as well as reaching the Ro32 in the GOM Classic Season 2. EffOrt was dubbed the “neo-sAviOr” at that time due to his game-style’s strong resemblance to sAviOr, who is also on EffOrt’s team.
EffOrt was first noticed by many foreign fans in a televised match against Fantasy on Medusa. At the time, Fantasy was known for his fearsome tech-based TvZ build that many Zerg players struggled against. EffOrt won handedly with a 3 Hatchery Zergling all-in attack, made even more memorable because he spammed "1a2a3a4a" in the pre-game chat, suggesting he would do some sort of all-in. He was also affectionately termed "Alien Zerg" at this time due to his distinctive facial features.
During the first two rounds of Shinhan Bank Proleague 08–09, EffOrt became the most frequently used Ace player by his team. While performing sub-par in the Shinhan Bank Winners League 08–09, going 3–6 as a whole, he came back to form in SPL 08–09 Round 4. Through this he emerged as one of the best players statistically of 2009. In this year, his strong performances in the 2009 Avalon MSL (advancing to the round of 8 before losing to Calm 0-3) and 2009 Bacchus OSL (advancing to the round of 16). EffOrt was also in the semifinals of the GOM Classic Season 3, but lost to teammate, Iris, getting swept 3–0. EffOrt managed to defeat July in the 3rd place play-off, 3–1, which earned him a place at BlizzCon 2009. At the BlizzCon event, EffOrt earned the championship by defeating ZerO.
EffOrt continued his strong performances into the 09–10 Proleague Season. He finished with 10 wins and 3 losses, including 2 wins and 1 loss in ace matches with victories over JangBi and ZerO. Despite his recent form, in the 2009 NATE MSL, EffOrt was eliminated in the round of 32, losing 2 straight games to RuBy and Firefist. In the 2009 EVER OSL, EffOrt defeated Frozean in two straight games in the round of 36, qualifying him into what many saw as the season’s Group of Death in the round of 16. In that group, EffOrt was defeated by Zerg opponents Shine and Calm to be eliminated from the Starleague, although his defeat of Fantasy eliminated the Terran player, thus preventing Fantasy from a fourth consecutive OSL semifinal.
In Round 2 of the Proleague 09–10, EffOrt continued to show strong play, finishing the round with an 8–6 record and, once again, a 2–1 record in ace matches. This gives him a 19 win, 10 loss record going into Winners League and the third most wins of the league.
In the 2010 Korean Air OSL, EffOrt defeated Flash, the heavy favorite, 3-2 after a 0-2 deficit. His OSL run included a 7 hour long tiebreaker in the group stage including EffOrt, go.go, and Shine.
In September 2010, EffOrt announced his retirement, citing publicly that he had achieved his goal as a progamer (to win a Starleague) and was seeking new challenges in life. A few months later, however, on March 2011, Hite Entus announced EffOrt would be returning after regaining pro-gamer license back on August 31, 2011. In January 2015, EffOrt revealed his retirement from and re-signing with CJ Entus was somewhat forced upon him. EffOrt described the retirement as a cost-saving measure tactic after having signed a new lucrative ￦90,000,000/year contract that was nullified, presumably signing for an alternate amount before returning. Notably, as part of these revelations, EffOrt also indicated his second retirement from CJ Entus in 2014 was also involuntary as the team justified his termination by falsely accused him of fixing matches.
In his first game back, EffOrt defeated Hyvaa on Outlier after Hyvaa attempted to engage EffOrt's Zerglings who had a concave defending his ramp. Hyvaa traded poorly, a Zergling counterattack put his fast expanding economy behind EffOrt's one base play, and this allowed EffOrt to easily win the air battle capturing the team's first victory of the 2011-2012 Proleague Season 1.
- Korean Air had specially made a commemorative airplane model for the Korean Air Starleague 2010 champion, Kim Jung Woo; read more.
- EffOrt had a stretch in 2009, in which he went 25–3 after the end of Winners League, including wins over Jaedong and Flash. This was the third best streak by a player of all time, beaten only by a similar run by iloveoov. (Flash has also since surpassed this streak when he went 27–3 from 2009.10.10 to 2009.12.25). This performance helped him win the Rookie of the Year award.
- EffOrt was the 2nd highest ranked player of the Minor League Season 1 going 6–1.
- EffOrt’s powerful play in 2009 has prompted popular YouTube commentator HuskyStarCraft to release the following parody video The Seven Things I Hate About Woo.
|In Premier Tournaments|
|2016-01-16||1st||VANT36.5 National Starleague||3 : 1||Bisu||$27,000|
|2010-05-22||1st||Korean Air Starleague 2010||3 : 0||Flash||$32,200|
|2009-08-03||3rd||GOMTV Averatec Intel Classic Season 3||3 : 1||July||$8,070|
|In Major Tournaments|
|2017-06-10||1st||SSL Classic Season 1||3 : 1||free||$8,680|
|2016-04-09||2nd||Terror Starleague Season 2||3 : 4||ZerO||$10|
|2015-09-13||1st||Spotimes Starleague||3 : 0||ZerO||$5277|
|2010-08-22||4th||WCG Korea 2010||0 : 2||Kal|
|2009-08-23||1st||2009 Blizzcon Invitational||2 : 1||ZerO||$25,000|
|In Minor Tournaments|
|2017-10-14||1st||Seoul Cup - OGN Super Match|
|2015-04-16||1st||41 Maki Starleague Season 1||3 : 0||HiyA||$140|
|Complete Results in any Tournament|
| 2009 EVER OSL
| Korean Air Starleague 2010
22nd May 2010-11th September 2010
| Korean Air Starleague Season 2|
|BlizzCon StarCraft: Brood War Champion|
| BlizzCon 2008
| BlizzCon 2009 StarCraft: Brood War Invitational
23rd August 2009 - 23rd October 2010
| BlizzCon 2010|
- Finished the 08–09 Proleague season with 39 wins and 21 losses, leaving him with one of the best records of the season.
- vs. Flash on Judgment Day, Shinhan Bank Proleague 09–10, Ro4 Week 6 Day 2 1st set or — an excellent play by EffOrt vs. Mech Terran before the Final match of the Korean Air Starleague 2010.
- vs. Flash SPL 08–09
- vs. Jaedong on Judgment Day, Shinhan Bank Winners League 09–10, Week 3 Day 5 2nd set
- vs. Jaedong on Neo Medusa, Shinhan Bank Proleague 08–09, Ro5 Week 2 Day 5 1st set
- Hey Kim Jung Woo — the thread on TL.net with an honorable song for Kim Jung Woo by hyst.eric.al (and with parody by HuskyTheHusky). [2010.05.25]