League of Legends Champions Korea (LCK) is the primary competition for League of Legends esports in South Korea. Contested by ten teams, the league runs two seasons per year and serves as a direct route to qualification for the annual League of Legends World Championship. The LCK is administered in cooperation between Riot Games and KeSPA.

The league was formerly named League of Legends Champions before undergoing a major restructuring in late 2014, which saw a change in the competition's format and a rebranding to its current name. OGN reserved exclusive broadcasting rights of the league until 2016 when rights were split with SPOTV Games.^{[non-primary source needed]} In 2019, Riot Games took over the broadcasting of LCK. In 2021 the LCK franchised, and Challengers Korea (CK) and the LCK promotion tournament were discontinued.

Teams from the LCK have won the World Championship a record ten times, including five consecutive titles from 2013 to 2017.

Following the launch of South Korea's League of Legends server in December 2011, cable broadcaster OnGameNet launched the country's first major League of Legends tournament in March 2012. Named The Champions Spring 2012, the tournament ran from March to May and was contested by a total of 16 teams. MiG Blaze was crowned the competition's inaugural champion after defeating their organizational sibling team MiG Frost in the finals. The Champions Summer 2012 followed later that year, with a rebranded MiG Frost, now known as Azubu Frost, claiming the title themselves. Azubu Frost, along with NaJin Sword, went on to represent South Korea in their first appearance at the League of Legends World Championship in October.

A tri-tournament annual circuit was soon set as the norm for the league's calendar year, now consisting of three seasons held in the winter, spring, and summer. Azubu Frost and NaJin Sword clashed early in 2013 in the finals of Champions Winter 2012–13, with the latter emerging victorious. Champions Spring 2013 and Champions Summer 2013 later followed, being won by MVP Ozone and SK Telecom T1 K respectively. SK Telecom T1 K went on to win the Season 3 World Championship later that year, becoming the first team from the league to do so.

SK Telecom T1 K became the first team to successfully defend their title the following year, sweeping Samsung Galaxy Ozone in the finals of Champions Winter 2013–14 to cap off an undefeated tournament run. Ozone's sibling team, Samsung Galaxy Blue, went on to win Champions Spring 2014 but were bested in the finals of Champions Summer 2014 by KT Rolster Arrows.

In October 2014, plans were announced for a drastic overhaul of the league's structure. League of Legends Champions was rebranded to League of Legends Champions Korea (LCK), and the winter season was abolished in favor of an annual circuit consisting of the Spring Split and Summer Split. The competition's format, which consisted of a 16-team tournament with a group stage progressing into a knockout stage, was changed to a 10-team league operating on a round-robin basis, with the top 5 teams qualifying for a playoffs bracket. Furthermore, organizations were prohibited from owning more than one team - in particular, this change most heavily affected KeSPA-affiliated teams, all of which operated two squads as part of a sibling team system - forcing numerous organizations to merge or disband rosters.

LCK Spring 2015 marked the debut of the league operating under its new format and identity. A newly minted SK Telecom T1, a product of the prior year's merger between SK Telecom T1 K and SK Telecom T1 S, swept the calendar year by winning both LCK Spring 2015 and LCK Summer 2015.