During the K League summer transfer window, a total of 59 additional players were registered; 22 in K League 1 and 37 in K League 2. The result of which is a combined 748 registered players in both K League divisions for the second half of the 2020 Hana 1Q K League season.

The K League summer transfer window opened on June 25th and closed again on July 22nd, a period of four weeks for teams to be able to sign and register new players. A total of 59 players were registered during that time.

In K League 1, a total of 22 players were registered. Eight free transfers, seven loans, four permanent transfers, and two players signing professional contracts for the first time. There was also one player returning from loan to their parent club. 

From K League 2's total of 37 there were 17 loan deals, 12 free transfers, five permanent transfers, one youth contract, and one first-year pro. In addition, there was one loan returnee. 

The total number of registered players in K League now stands at 748. K League 1 has 437 with teams in the top flight having 36.4 players each on average, and 347 in K League 2 to yield an average of 34.7 per team.

■ The return of familiar faces; Ki Sung-yueng, Cho Won-hee, Na Sangho

After 11 years in Europe Ki Sung-yueng returned to FC Seoul, Na Sang-ho joined Seongnam FC on loan and Cho Won-hee came out of retirement joining Suwon FC, two years after leaving Suwon Bluewings. Suwon FC also signed former Pohang Steelers midfielder Jung Jae-yong after a spell in Thailand. Also, experienced midfielder Kang Seung-jo returned to Gyeongnam after a spell in the Malaysia.

■ K League debutants arriving from overseas: Gu Sung-yun, Seo Young-jae

Korean international goalkeeper Gu Sung-yun joined Daegu FC after a lengthy spell in J.League and made his K League debut during the Sky Blues' 2-1 win over Gangwon at the end of June. In K League 2, Daejeon Hana Citizen signed left-back Seo Young-jae from 2. Bundesliga side Holstein Kiel. Seo stepped out onto a K League pitch for the first time during the Purples' 2-1 win over Jeju United in Round 12. In addition, Hwang Moon-ki joined FC Anyang after five years in Portugal with Académica, and Kim Dong-soo, who had spells in Germany with Lübeck, also joined the Violets. All of whom made their K League bows before the transfer window closed.

■ 'Title contenders' Ulsan and Jeonbuk's Summer Transfer Window

This season's title contenders, Ulsan Hyundai and Jeonbuk Hyundai Motors, both added reinforcements during the transfer window. Ulsan brought in Korean international left back Hong Chul from Suwon Bluewings, while Jeonbuk brought central midfielder Shin Hyung-min back. Not only that, the Green Warriors also added former English Premier League winger Modou Barrow from Reading and Brazilian targetman Gustavo from Corinthians.

■ Suwon FC, FC Anyang the two busiest clubs

FC Anyang and Suwon FC both added six new players to their squads, them most in both K League 1 and 2. In K League 1, however, Jeonbuk and Incheon both signed three players, the most of any in the top flight. Gustavo's international clearance arriving on July 30th resulted in a fourth for Incheon.