BoA's multilingual skills (she speaks Japanese and conversational English along with her native Korean and has recorded songs in Mandarin Chinese) have contributed to her commercial success in South Korea and Japan and her popularity throughout Asia. She is one of only two non-Japanese Asians who have had million-selling albums in Japan and is one of only two artists to have six consecutive number-one albums on the Oricon charts.
In early 2001, BoA released her first mini-album Jumping into the World. After its release, she took a hiatus from the Korean music industry to focus on the Japanese market. During this time she struggled to solidify her skills in Japanese.
BoA began her Japanese music career singing at the Avex-owned club Velfarre. In 2001, she released her debut Japanese single, a Japanese version of the song, "ID; Peace B" (originally from the eponymous album). The single reached the number-twenty position on the Oricon chart and was followed by "Amazing Kiss", "Kimochi wa Tsutawaru", and "Listen to My Heart"; the last became the singer's first single to enter the Oricon chart's Top Five. After the September 11, 2001 attacks, BoA recorded the charity single "The Meaning of Peace" with Kumi Koda as part of Avex's Song+Nation project to raise funds for the families of the attack victims. Her Japanese debut album, Listen To My Heart, was released on March 13, 2002. The album was a breakthrough in BoA's career: it debuted at the top spot on the Oricon and became an RIAJ-certified million-seller as well as the first album by a Korean artist to top the charts. A single, "Every Heart -Minna no Kimochi-", was released on the same day as the album. Later in 2002, BoA released two Korean studio albums, No.1 and the mini-album Miracle.
BoA reinvented her image on her fourth Korean album, My Name (2004); she left the "cute" and "youthful" style that had characterized previous years and presented herself as "sexy" and "sultry". Her fifth Korean album, Girls on Top, continued her image change. The album portrayed the singer as more "mature and self-confident"; the "bohemian" look of the cover photograph represented "freedom and depth", while music videos and album photographs that portrayed BoA in traditional Korean dress brought the "idea of Korean womanhood" into her music.
BoA's fifth Japanese studio album, Made in Twenty (20) (2007), continued her transition from a "teenage girl" image to a more mature image. The album, which contained R&B and dance songs as well as ballads, debuted at the top of the weekly Oricon charts, making the album her sixth in a row to do so. On March 31, 2007, she launched a nationwide tour of Japan in support of the album. The tour, which sold about 70,000 tickets, was, according to BoA, "the biggest concert" she had ever given. Two tracks from the singles of Made in Twenty (20) were used as theme songs; "Your Color", from the single "Nanairo no Ashita~brand new beat~ / Your Color" (2006), was used as the ending theme song for the Japanese release of the Xbox 360 game Ninety-Nine Nights. "Key of Heart", from the single "Key of Heart / Dotch", was the ending theme of Over the Hedge in Japan. She also released an English version of "Key of Heart," which was only available on the first press edition of the single. The album's last single, "Winter Love" (2006) became another number-one single for the artist.
Later in 2007, Anycall (a Samsung brand) signed BoA, Xiah Junsu (of DBSK), Tablo (of Epik High), and jazz pianist Jin Bora onto "AnyBand", a band created specifically to promote Anycall. The band released only one single, "AnyBand".
With her sixth Japanese album, The Face (2008), BoA took more creative control over her music. She began writing her own lyrics and co-composed one of the songs ("Girl in the Mirror"). Influenced by a The Jackson 5 album, BoA used mostly electro-pop in the album. Additionally, BoA included "happy spring" songs ("Sweet Impact" and its B-side, "Bad Drive" (2007), the album's first single), a guitar-driven "groovy dance" song ("Lose Your Mind" (2007)), and ballads. Lyrically, BoA focused mainly on love, though "be with you." (2008) was about a person's relationship with his dog. The album debuted at the top of the weekly Oricon charts, making BoA one of only two artists in Japan to top the Oricon weekly charts six consecutive times (the other being Ayumi Hamasaki, who has eight consecutive number-one albums). Following The Face, BoA released her twenty-sixth single, "Vivid", on June 4, 2008.
BoA has collaborated with "high-profile" artists. Among the Japanese artists she has performed with are the hip-hop group m-flo (for the single "The Love Bug"), Kumi Koda, and house DJ Mondo Grosso. She has performed with Western artists: the song "Flying Without Wings" from her album Next World was a collaboration with Irish band Westlife covering the original song; the Bratz single "Show Me What You Got" was performed with Howie D of the American band Backstreet Boys. Other artists she has collaborated with are the Soul'd Out, Dabo, Verbal (of m-flo), RAH-D, and Yutaka Furakawa (of the band Doping Panda). American rock band Weezer covered "Meri Kuri" on the album Weezer (The Red Album).
BoA is a "top artist" in South Korea and Japan; her popularity in the latter is attributed to her linguistic skills (she speaks and records in Japanese, Korean, and English) and a Japanese interest in Korean pop culture started in the early 2000s when the two countries began promoting cultural exchanges. BoA's popularity extends throughout Asia; she has fans in China, Hong Kong, Taiwan, and Singapore. She has expressed plans to enter a global market; she stated in an interview, “I will [...] get recognition in the U.S. and Europe to become a world-renowned Diva. In June 2006, the music video of her Korean song "My Name" became the first music video ever shown on MTV K, an MTV music channel directed at Korean Americans.
Because of her wide appeal, BoA has appeared in advertisements for many brands. Among the brands she has promoted are Olympus, Nike, L'Oreal, Japanese cosmetic company Kosé, Sketchers, and GM Daewoo. Three of her songs have been used as themes. "Every Heart" was used as the theme for the anime InuYasha; "Key of Heart" was the theme song for the Japanese release of Over the Hedge; and "Your Color" was the theme song of the video game Ninety-Nine Nights. Her widespread popularity has also made her a "cultural ambassador"; she has represented South Korea in inter-Asian musical events and has appeared in an Oxford University Press English-language textbook.