2018–2019: International breakthrough and first world tour
On January 6, 2018, Blackpink released the first episode of their first reality show, Blackpink House, which comprised 12 episodes released throughout 2018 following the four members spending 100 days of vacation as they moved into their new dorm, via their official V Live and YouTube channels. On March 28, Blackpink re-released their debut Japanese EP under the name Re:Blackpink. The digital version included the same songs as the original release, while the physical version included a DVD of all their music videos and six songs in the Korean language.
On June 15, 2018, the group released their first Korean-language EP, Square Up. In South Korea, the EP debuted at number one on the Gaon Album Chart and was certified platinum by the Korea Music Content Association (KMCA) for selling 250,000 units. Square Up brought the group their first entry and the highest-charting album by a female Korean group at the time of its release on the Billboard 200, debuting at number 40. The EP also topped the Billboard World Albums chart and led Blackpink to become the first female Korean group to reach number one on the Billboard Emerging Artists chart. The EP's lead single, "Ddu-Du Ddu-Du", peaked at number one on the Gaon Digital Chart, while "Forever Young" peaked at number two; both songs were certified platinum by the KMCA for surpassing 2,500,000 downloads and 100,000,000 streams in the country. In the United States, "Ddu-Du Ddu-Du" debuted at number 55 on the Billboard Hot 100 and became the highest-charting song by a Korean girl group in the country at that time, surpassing the record set by "Nobody" by Wonder Girls in 2009. It additionally marked the first time a Korean girl group entered the US Streaming Songs chart, entering at number 39. The song was certified gold by the Recording Industry Association of America (RIAA) in August 2019, making Blackpink the first Korean girl group to receive a certification in the country. In the United Kingdom, "Ddu-Du Ddu-Du" debuted at number 78 on the UK singles Chart and made Blackpink the first female Korean group to enter the chart. YouTube's official tally saw the music video for "Ddu-Du Ddu-Du" garner a total of 36.2 million views within 24 hours after its release, making it the most-viewed online video in the first 24 hours by a Korean act and the second most-watched music video of all time in the first 24 hours of release at the time. It became the most-watched music video by a South Korean group in January 2019 and became the first K-pop group music video to surpass one billion views in November 2019 and two billion views in January 2023. "Ddu-Du Ddu-Du" was named the Song of the Year by South Korean research company Gallup Korea's annual public survey conducted in 2018.
Blackpink embarked on their sold-out first Japan tour, Blackpink Arena Tour 2018, in Osaka from July 24 to 25 to promote their Japanese EP. The tour was initially set for six shows across Osaka, Fukuoka and Chiba, but an additional show in Chiba was added due to overwhelming demand. A final tour stop was later added for December 24 at the Kyocera Dome Osaka as a Christmas gift for fans, where Blackpink performed to a sold-out crowd of 50,000 people. On September 12, it was announced that the group would hold their first concert in Seoul, Blackpink 2018 Tour [In Your Area] Seoul x BC Card, at the Olympic Gymnastics Arena. The concert was the first show of the In Your Area World Tour, which continued throughout 2019 and early 2020 in North America, Europe, Oceania and Asia. By the end of its run, the tour had become the highest-grossing tour by a Korean girl group.
On October 19, 2018, English singer Dua Lipa released "Kiss and Make Up" with Blackpink, a new track on the re-released edition of her self-titled debut album. "Kiss and Make Up" became the group's second entry on the UK singles Chart, peaking at number 36, which made it the first top-40 hit by a female Korean group. It also debuted at number 93 on the Billboard Hot 100, marking Blackpink's second entry on the chart and making them the only Korean girl group to score multiple entries on the chart. The song was certified silver in the UK by the British Phonographic Industry (BPI), marking the first time a Korean group received a certification in the UK. It was also the first song by a Korean group to be certified platinum by the Australian Recording Industry Association (ARIA). On October 23, the group signed with Interscope Records in a global partnership with YG Entertainment; their representation outside Asia was to be handled by Interscope and Universal Music Group. In November 2018, Blackpink announced additional tour dates for their In Your Area World Tour, which covered various dates across Asia from January to March 2019. Jennie made her solo debut with her single "Solo" at Blackpink's Seoul concert on November 11; both the song and its official music video were released the following day. Their first Japanese studio album, Blackpink in Your Area, was made available digitally on November 23 and physically on December 5. The album included Japanese versions of all of their previous releases and debuted at number nine on the Oricon Albums Chart.
Blackpink made their American debut at the Universal Music Group's 2019 Grammy Artist Showcase, an invite-only event at the ROW in Downtown Los Angeles on February 9, 2019. The group subsequently appeared on several American television shows, including The Late Show with Stephen Colbert and Good Morning America. That March, they became the first K-pop girl group to cover Billboard magazine. Blackpink's third extended play, Kill This Love, was released on April 5, 2019, alongside its lead single of the same name. In South Korea, the EP debuted at number three on the Gaon Album Chart and was certified 2× platinum by the KMCA for selling 500,000 units in the country, while the lead single peaked at number two on the Gaon Digital Chart and was certified platinum for surpassing 100,000,000 streams in the country. Kill This Love also debuted at number 24 on the Billboard 200, while the lead single reached number 41 on the Hot 100, becoming the highest-charting releases by a female Korean group on the two major Billboard charts. The EP also became Blackpink's second number-one album on the Billboard World Albums chart. The song's music video broke the record for the most views within 24 hours on YouTube, accumulating 56.7 million views in that time. "Kill This Love" ranked at number 66 on Billboard's list of the 100 Best Songs of 2019.
Following the EP's release, Blackpink performed at the 2019 Coachella Valley Music and Arts Festival on April 12 and 19, 2019, making them the first female K-pop group to do so. The group's Coachella set was well received by both critics and fans alike, with Gab Ginsberg of Billboard calling the show "electrifying" and "unforgettable". On October 16, 2019, a Japanese version of Kill This Love was released to the Japanese market, peaking at number five on the Oricon Albums Chart. The group embarked on a variety of promotional activities in Japan, including appearances on Japanese music television programs TV Asahi's Music Station and Fuji TV's Love Music. In January of the following year, Blackpink was voted Paper magazine's 2019 K-pop Sensation of the Year in their annual Break the Internet Awards list.
