The team won the 2000 World Junior Baseball Championship in Edmonton, Alberta, Canada, and Lee led the attack alongside Kim Tae-kyun, Choo Shin-soo (the eventual MVP of this event) and Jeong Keun-woo as a cleanup hitter by racking up 3 home runs.

In the 2006 season, Lee won the league's Triple Crown with a .336 batting average, 26 home runs, and 88 RBIs.

On August 13, 2010, Lee wrote a new chapter in Korean baseball by hitting a home run in eight straight games in the league.

The eighth home run was hit at an away match against the Kia Tigers in Gwangju in the top of the seventh inning when he sent former Major Leaguer Aquilino López's fifth pitch over the left fence of Moodeung Stadium.

This tied the existing record in world professional baseball shared by Ken Griffey Jr. in 1993, Don Mattingly in 1987 and Dale Long in 1956.

[5] On August 14, 2010, Lee set a world record by hitting a home run in his ninth straight game when, in the second inning of Giants' second away match against the Tigers, he blasted a three-run homer off Tigers reliever Kim Hee-girl over the center fence of Moodeung Stadium.

In the 2010 season, Lee enjoyed one of the most dominant offensive seasons in world professional baseball history, leading the KBO in seven offensive categories (batting average, HRs, RBIs, runs scored, on-base percentage, slugging percentage and hits), which made him a Septuple Crown winner (7관왕).

On July 20, 2012, at the Osaka Dome, Lee won the NPB Home-run Derby against Wladimir Balentien of the Tokyo Yakult Swallows.

[8] On April 8, 2016, Lee recorded his first career major league hit, a home run off of Eric Surkamp in a game against the Oakland Athletics.

[11] On June 10, 2016, Lee recorded back-to-back home runs off of Derek Holland, totaling 4 RBI to propel the Mariners to a 7–5 victory over the Texas Rangers.