Faker was born in Seoul on May 7, 1996. He and his brother were raised by their grandparents and their father, Lee Kyung-joon, in Gangseo District, Seoul. Faker always loved puzzles and video games, often playing custom maps for Warcraft III and the MOBA Chaos during his teenage years. He discovered League of Legends in late 2011, and quickly became adept at the game. He attended Mapo High School, the same high school that Deft of DragonX attended, but dropped out to join SKT T1 K and pursue a career in esports.

Faker was picked up by SK Telecom T1 K in 2013 as their starting mid laner. SKT T1 K dominated the Korean scene and in October 2013 Faker led them to win their first League of Legends World Championship. Later in the HOT6iX Champions Summer 2013, Faker cemented his status as a brilliant player due to his perfect outplay against KT Rolster Bullets mid laner Yoo “Ryu” Sang-wook, which would then become one of the most iconic moments in League of Legends history.

In 2014, SK Telecom T1 K followed their success through in the OGN winter season, making the entire run without dropping a single game. They would then go on to win All-Star Paris 2014. However, their Winter season success did not follow through and during the Spring and Summer seasons, SKT T1 K failed to qualify for the 2014 World Championship. In the following offseason, Riot Games changed the team regulations so that each organisation can only have one team participating in each league. This led to the merger of SKT T1 K and SKT T1 S, and the subsequent departures of Impact and Piglet for the NA LCS. The new team would compete under the name SKT T1.

Between Seasons 4 and 5, many top Korean League of Legends players, including the entire world champion team, Samsung Galaxy, left Korea to play on Chinese teams for higher salaries. Faker on the other hand, declined an offer of over $1,000,000 by a Chinese team, preferring to stay in Korea on SKT. In November 2014 it was reported that Faker had declined contract offers from several Chinese companies including one offer of ₩500 million ($425,403 USD) for streaming.

Throughout 2015, Faker shared the mid lane position with Lee “Easyhoon” Ji-hoon. Depending on the team composition SKT wanted to play, either one of the players could be substituted into the game. Faker had many notable performances in the LCK such as a pentakill against NaJin e-mFire with his LeBlanc. SKT ended the summer split in first place and advanced to the world championship.

At the 2015 World Championship, Faker and his team won while only dropping one game in the finals for a record of 15–1 throughout the tournament.

Faker and his team started off the 2016 Season by winning the LCK Spring Split. With this victory, SKT was guaranteed a spot in the 2016 Mid-Season Invitational. At that point in time, MSI was the only major international tournament they had yet to win. They were heavily favored coming into the tournament, but were initially unable to perform up to their usual standards, unexpectedly losing several games in the group stage. However, they managed to turn things around during the elimination round and eventually clinched the title by sweeping the North American team, Counter Logic Gaming, in the finals.

On July 11, 2016, Faker became the first player to reach 1,000 kills in the LCK. His 1,000th kill was on MVP Beyond’s Reksai, which he achieved on Malzahar.

SKT placed third in the 2016 LCK Summer Split, but still qualified for the 2016 World Championship through circuit points. The team swept through the group stage and advanced towards the playoff round. In the semifinals they defeated the ROX Tigers in a close 3–2 series. In the finals they defeated Samsung Galaxy in another close 3–2 series, winning their third world championship title. Faker was voted as the Most Valuable Player of the tournament.

On February 6, 2017, Faker recorded his first live stream on Twitch and had a peak viewership of 245,100, setting a record at the time for the most views for a single streamer in the history of the site. However, this record was broken in early 2018 by another League of Legends streamer named Tyler1.

At the 2017 Mid-Season Invitational, SKT topped the group stage with a 8–2 record. SKT swept Flash Wolves 3–0 in the semifinals and defeated G2 Esports 3–1 in the finals to become the first team to win the Mid-Season Invitational back to back.

At the 2017 World Championship, SKT were still considered by many to be strong favorites to lift the cup for a third consecutive time despite not winning the LCK Summer Split. After a dominant group stage conceding just a single loss, SKT narrowly defeated Misfits and Royal Never Give Up in the quarterfinals and semifinals respectively, before having to face Samsung Galaxy in a repeat of the previous year’s final. SKT’s fate was sealed after Faker was caught by a flash Varus ultimate by Samsung’s AD carry Ruler, resulting in Samsung Galaxy clean sweeping SKT 3–0, ending the SKT domination at the World Championship. Faker himself was shown to be visibly upset after the loss, and had to be consoled by his teammates to shake the Samsung Galaxy players’ hands post-game. However, this caught the attention of many League of Legends fans throughout the world, with much support and many tributes being given to the team’s legacy and Faker for his continued success.

Faker played his 400th match in the LCK on July 17, 2018. They successfully defeated their opponent, MVP, 2–1.

SKT finished fourth in the 2018 Korea Regional Finals, failing to qualify for the 2018 World Championship.

On November 20, 2018, it was announced that Faker had re-signed with SKT for another three years.

On April 13, 2019, SKT won the 2019 LCK Spring final, earning Faker his seventh LCK title.

In May 2019, SKT represented the LCK at the 2019 Mid-Season Invitational. They finished the group stage in second place but lost 2–3 to G2 Esports in the semifinals.

On July 7, 2019, SKT, alongside with three other LCK teams, won their league’s first Rift Rivals championship title after defeating LPL teams by 3–1. After winning his first Rift Rivals title, Faker became the first and only player to have won all of the League of Legends international tournaments (Mid-Season Invitational, World Championship, Rift Rivals, All-Star) organized by Riot Games.

Faker played his 500th match in the LCK on August 21, 2019, during the LCK Summer Playoffs. He won his 500th game against Afreeca Freecs with Qiyana, with a KDA of 7/1/14. He won his eighth LCK title along with his team members on August 31, 2019 in the 2019 Summer LCK Final. His team qualified as the LCK’s first seed for the 2019 League of Legends World Championship.

On October 27, 2019, Faker achieved his 100th international win after defeating Splyce at the 2019 World Championship.

At the 2019 World Championship, SKT was once again defeated by G2 Esports in a semifinals series, losing 1–3.

On February 18, 2020 T1 announced that Faker had re-signed with them for three years, in which his contract will last until the year 2022. He also became a part owner of T1 Entertainment and Sports.

On March 5, 2020, Faker became the first player to have reached 2,000 kills in the LCK. The champion used when achieving his 2,000th kill was Zoe.

On April 25, 2020, Faker claimed his ninth LCK title after he and his team defeated Gen.G at the 2020 LCK Spring finals.