Due to his commercial success, Kim is considered one of South Korea's biggest Hallyu stars of the early 2010s.

[5] Kim made his debut as a member of SS501 on June 23, 2005, with the group's first EP, Warning, released by DSP Media.

[17] Tony Moly, a cosmetics brand for which Kim had been a spokesmodel since 2006, saw a 30 percent sales increase in 2009, which the company attributed to the popularity of the show.

[18] Kim's contract with Tony Moly ended in 2010,[19] and he became the spokesmodel for another cosmetics brand, The Face Shop, later that year.

[22][23] At the end of 2010, Kim was chosen to represent South Korea at the opening of the 2010 Asian Games in Guangzhou, where he performed the anthem "Sunshine Again" with singers from Chinese-speaking countries.

[30] The EP debuted at number five on Billboard's World Chart,[31] and was the 10th best-selling album of the year in South Korea with over 100,000 copies sold.

[40][41] In March 2012, Kim was appointed the honorary ambassador for United Nation's Korean Campaign on Contributions to Social Welfare.

[53] On January 6, 2013, Kim kicked off a Japanese tour called Unlimited at the World Memorial Hall in Kobe, where he performed with a live band.

[55] On March 2, Kim performed at the U-Express Live 2013 at the Makuhari Messe in Japan with artists including Ringo Starr & His All-Starr Band, Far East Movement, Naoto Inti Raymi and Kara.

[63][64] On October 20 and 21, Kim held two concerts at the Makuhari International Exhibition Hall in Japan, attended by 20,000 fans.

[70] At the end of June, he began a world tour that included stops in Taiwan, China, Japan, Thailand, Mexico, and Peru.

[75] While he was in the military, The Best of Kim Hyun Joong, a Japanese greatest hits album celebrating his 10 years in music industry, was released.

He performed in Bolivia, Chile, Mexico, South America, Japan, Thailand and Macau and the tour concluded in 2018.

On February 21, he appeared in the cover of the Korean Wave Japanese Magazine Hanryu Pia for the fourth time.

The title track of the Album and its music video features vocals and appearances from Kim Hyun-Joong's fans all over the world.

"[108] This was later rescinded in 2016 when the Republic of Korea's army and civil courts acquitted Kim of these charges due to evidence that came to light.

[109] On November 12, 2020, the Supreme Court of Korea ordered “A” to pay Kim Hyun Joong 100 million won (approximately $89,700) in damages, upholding the verdict from the first and second trials in which they stated, “There is no evidence that ‘A’ suffered a miscarriage due to abuse, or that he had pressured her to have an abortion.

Kim stated via a press release that he had not seen Choi since she told him that she was pregnant in January, and could not confirm if he was the father since she had not been in touch.

[113] In December 2015, a paternity test revealed that Kim was the father of a baby that Choi had given birth to in September of that year.

[116][114] Kim later filed and won a 100 million KRW counter-suit against Choi for defamation, with the court ruling that there was circumstantial evidence that she was not pregnant in 2014.

[79] Prosecutors filed criminal charges against Kim's ex-girlfriend, Choi, for attempted fraud and defamation in January 2017.

Choi was found to have filed a civil lawsuit while knowing that her allegation that Kim had caused her damage, such as forced abortion, was false.

[120] In March 2017, Kim was charged with drunk driving after police found him asleep in his car at a traffic light in Seoul.

[121][122] Following the Fukushima Daiichi nuclear disaster in March 2011, Kim donated 100 million KRW to earthquake relief efforts in Japan.

[127] In 2019, during his BIO-RHYTHM World Tour in Thailand, he donated 9.7 million KRW to support the tuition fees for the students from Sumakee Learning Center, Mae Sot District, Tak Province.