In mid-2019, he released his solo debut extended play (EP), Color on Me, which was a commercial success that topped South Korea's Gaon Album Chart.

He then released the third and final chapter of his "color trilogy", Yellow (2021), which topped the Gaon Album Chart and contained his first domestic number one single titled "Antidote".

[7] After spending his childhood and most of his teen years with his birth name, he decided to legally change it to Daniel due to family and friends having difficulty pronouncing Eui-geon.

[15][16] Having been raised in a single parent household, Kang revealed that the "tuition [at his arts high school] was really expensive" for his mother who, at the time, was not feeling healthy.

[21] One of the most notable moments during his time as a trainee was his appearance on Her Secret Weapon, performing "Invitation" by Uhm Jung-hwa, where he served as a backup dancer to Fiestar's Cao Lu and Spica's Sihyun.

[29][30] Following the conclusion of promotions for the EP, Kang was chosen as the first male celebrity to appear on the cover of InStyle Korea fashion magazine in its 14-year history for its October 2017 issue.

[32][33] Kang was involved in several prominent solo activities the following year, most notably as the main model for Davichi's "Days Without You" (너 없는 시간들) music video[34][35] and as a continuing cast member on the second season of MBC's It's Dangerous Beyond the Blankets.

[38] Although he concluded his contract with Wanna One on December 31, he still appeared with the group until its official farewell concerts that were held at the Gocheok Sky Dome between January 24 to 27 of the following year.

[41] On May 10, the Seoul Central District Court ruled in favor of Kang, allowing the suspension of his contract and his pursuit of individual activities as a celebrity without any interference from the company.

[75] In November, Konnect opened pre-orders for Kang's first artbook Never Standing Still - It's Time to Shine in collaboration with Paul McCartney's personal photographer, MJ Kim.

[88][89] In the same month, Kang was selected as the fixed MC for Mnet's first-ever female dance crew competition show Street Woman Fighter.

[95] In December, he reunited with nine other members of Wanna One for a special performance at the 2021 Mnet Asian Music Awards that included a new single by the group titled "Beautiful (Part.3)".

[100][101] Having previously turned down several offers to appear in Korean dramas, Kang revealed that the idea of working alongside people his age persuaded him to give the show's proposal a try.

[104] The following month, Kang performed his lead single "Antidote" on the Recording Academy's Press Play At Home as the first K-pop solo artist to appear on the series.

[117] He then made his Japanese debut under Warner Music Japan with the release of his Joy Ride EP on October 5 supported by the digital single "TPIR" featuring Miyavi.

[124] Held in Las Vegas, Kang performed at the We Bridge Music Festival and participated in the three-day exposition hosted by the Grammy Museum on April 21.

[135] Writing for Billboard, Jessica Oak noted that "Kang Daniel has elevated himself to a top-tier celebrity status that only a handful of artists can ever achieve" and further described him as "one of the highest-earning and most significant male solo acts in K-pop".

[136] In a segment dedicated to his domestic popularity, SBS's Late Night Entertainment News described him as "more than a top idol star" and additionally noted that "he created a craze" that was recreated in an episode of SNL Korea.

[145][146] His national influence was further seen as South Korean Olympic medalists Kim Kyeong-Ae,[147] Lee Da-bin,[148] and Hyun Jung-hwa[149][150] declared themselves fans of the artist.

[151] During an interview with Netflix Korea, Sweet Home actress Park Gyu-young revealed that she was inspired by Kang's pink hair color while he was on the second season of Mnet's Produce series for her character Yoon Ji-soo.

[155] In January 2019, Kang set a Guinness World Record for the "fastest time to gain one million followers on Instagram" (11 hours and 36 minutes after joining).

[180] Expanding its lineup of artists, singer-songwriter and producer Chancellor, former GFriend member Yuju, and dance crew We Dem Boyz (WDBZ) that appeared on Street Man Fighter each signed exclusive contracts with Konnect Entertainment.

[189][190] In July 2019, Kang became the model for South Korean telephone company, KT Corporation, advertising the Samsung Galaxy Note 10 Aura Red.

[221] In January 2018, two months after Kang was seen wearing a duffel coat designed by LAP to the Incheon International Airport, it was announced that he became the official model of the fashion brand.

[197] Their collaboration was seen on the October 2019 issue of High Cut fashion magazine, where Kang was the cover model on four different versions and sported Calvin Klein Jeans apparel.

[237] In November 2018, photographer Cho Sei-hon selected Jung Woo-sung and Kang Daniel as two people he thought had positive influence in South Korea for his last Letter from Angels exhibition, a 16-year adoption awareness campaign.

[239] On December 10, 2018, Kang donated ₩12.1 million ($10,400) for his birthday to the Miral Welfare Foundation to be used for low-income vulnerable groups' medical bills and living expenses.

Ahead of Christmas, Kang donated ₩30 million in his fan club's name to The Snail of Love, a social welfare group for the deaf and hard of hearing.

[244] On February 28, 2020, Kang made a personal donation of ₩50 million ($41,000) to Hope Bridge Disaster Relief to be used to purchase goods such as health masks and hand sanitizers to prevent the spread of COVID-19.

"[246] On April 17, Kang went to The Snail of Love's office to visit the first of ten children who will receive a cochlear implant under the auspices of his and his fan club's names and provided her with gifts.