In August 2017, JYP Entertainment (JYPE) officially announced the agency's new reality survival show to launch a male idol debut project. More details and teasers were released in the next two months, including the show's title—Stray Kids. Prior to its premiere on October 17, JYPE released Stray Kids' first music video for a song titled "Hellevator", which was later released as a digital single. Two members, Lee Know and Felix, were eliminated from the group, but all nine members ended up in the final line-up.
Before the official debut of Stray Kids, the nine members were chosen as new models to endorse Jambangee Jeans in 2018, which was announced on February 13 with the brand's spring collection. On June 26, they were selected as an exclusive model of Ivy Club for the 2018 Fall semester. On July 19, they received for the first set of their CF with Minute Maid Sparkling. Five days after their first CF, they were selected to be promotional models for CGV "Youth Brand Festival" from July 24 to August 31. On September 19, Stray Kids has been chosen as the newest ambassador of Lotte Duty Free. It was announced at Lotte Duty Free official YouTube and Instagram accounts. On October 16, Stray Kids became the new model of the Korean sportswear brand “Pro-Specs”.
Originally a nine-piece group, member Woojin left Stray Kids due to undisclosed personal reasons in October 2019. The group released their extended play Mixtape in January 2018 and officially debuted on March 25 with I Am Not.
Along with the launch of Stray Kids' official website, JYPE announced the release of the group's pre-debut extended play (EP) titled Mixtape. It contains seven tracks co-written and co-composed by the members, including "Hellevator" and other songs that they performed during the show. The EP, along with the performance video of its second track titled "Beware" (Korean: Grrr 총량의 법칙), was released on January 8, 2018, while the performance video of "Spread My Wings" (Korean: 어린 날개) was uploaded online a week later. It debuted at number 2 on Gaon's Album Chart and Billboard's World Albums chart.
On June 17, 2019, Stray Kids was chosen as the newest ambassador of Talk Talk Korea Contest in 2019, and June 18, they were appointed as an honorary ambassador by the Korean Culture and Information Service, Ministry of Culture, Sports and Tourism.
On March 5, JYPE announced the group's third comeback on March 25, 2019 with the release of their fourth extended play Clé 1: Miroh, in commemoration of the first anniversary of the group's debut. The group earned their first music show win on 4 April on M Countdown for the album's lead single, "Miroh." On June 19, the group released their first special album Clé 2: Yellow Wood, along with title track "Side Effects" (Korean: 부작용) between the American leg and the European leg of their first world tour.
On October 28, 2019, Woojin left the group and terminated his contract due to personal circumstances. On February 27, 2021, Hyunjin went on an official hiatus due to bullying allegations against him.
Stray Kids released the first English version of "Double Knot" and "Levanter" as the digital single Step Out of Clé, along with "Double Knot" English version music video on January 24, 2020.
Stray Kids made an official Japanese debut on March 18, 2020 with compilation album SKZ2020 in Japan and South Korea, with the new record of previous songs and including Japanese version of "My Pace", "Double Knot" and "Levanter" (風) that released as single before
Stray Kids released the Mixtape Project second digital single titled "Mixtape: On Track" (바보라도 알아) on March 26, 2020
On June 3, 2020, Stray Kids released their first Japanese single album titled "Top". It is used as the theme song for the anime Kami no Tō -Tower of God-. A Korean version was released on May 13, and an English version on May 20.
On June 17, 2020, Stray Kids released their first studio album called Go Live (GO生) with title track "God's Menu" (神메뉴), and included the Korean versions of "Top" and "Slump" and previously released singles “Gone Days" and "On Track". Go Live became the group's best-selling album, debuting atop the weekly Gaon Album Chart, and sold 243,462 copies by the end of the month to take number 5 on the monthly Gaon Album Chart. The album then received its Platinum certification from the Gaon Chart for selling more than 250,000 copies on August 2020, becoming the group's first album to do so. The lead single "God's Menu" became the group's first single to appear on the weekly Gaon Download Chart, debuting at number 144.
On November 2020, Stray Kids was chosen to become Shopee Indonesia brand ambassador for the 11.11 Big Sale and 12.12 Birthday Sale.
On November 4, 2020, Stray Kids released their first Japanese extended play titled All In with the lead single "All In" and also included the Japanese versions of "God's Menu" (神メニュー) and "Back Door", and their first Japanese single "Top".
On February 1, 2021, Stray Kids was chosen to become a new model of the brand Clio Cosmetics. On June, the group was chosen to become a new model of the Japanese clothing brand Wego.
Stray Kids held and broadcast the first official fan meeting, Stray Kids 1st #LoveSTAY 'SKZ-X' on February 20, 2021 via V Live. On March 18, the group also broadcast the first Japanese fan meeting for first anniversary of Japanese debut, STAYing Home Meeting.
As of May 2021, Stray Kids has seven active members: Bang Chan, Lee Know, Changbin, Han, Felix, Seungmin and I.N.