[1] Soon thereafter, Ueto joined the talent agency Oscar Promotion and began taking singing, dancing and acting lessons.

The group disbanded in 2002 and later that year, Ueto signed with Pony Canyon and released "Pureness", her debut single as a lead artist.

Her portrayal of a high school student with gender dysphoria garnered critical acclaim and led to several leading roles and advertising endorsements, establishing Ueto as one of Japan's most recognizable faces.

[4] Ueto ventured onto the big screen as the lead in Ryuhei Kitamura's 2003 blockbuster Azumi, which earned her a nomination for a Japan Academy Award for Best Actress.

She went on to star in its sequel, Azumi 2: Death or Love (2005), and Thermae Romae (2012), the adaptation of Mari Yamazaki's manga series of the same name.

In 2000, Ueto portrayed the supporting role of Momo Fuchigami in the Fuji TV drama Namida o Fuite, starring Yōsuke Eguchi.

In 2001, Ueto appeared on the annual Victor Kōshien poster, which, in the past, kick-started the careers of Noriko Sakai and Miho Kanno.

[10] Later that year, she was cast in the role of Nao Tsurumoto, a student suffering from gender identity disorder (GID), in the sixth season of the TBS drama 3-nen B-gumi Kinpachi-sensei.

[11] In January 2002, it was announced that Ueto would continue her music career as a solo artist under Pony Canyon subsidiary label, Flight Master.

The program would go on to last four-and-a-half years, changing names after each of her birthdays to Eighteen's Road, Nineteen's Nine, Hatachi ni High Touch!, and 21 Peace!.

[23] In July 2003, Ueto landed her first TV leading role in the TBS drama Hitonatsu no Papa e, for which her fifth single, Kanshō, served as theme song.

[40][41][42] Ueto was appointed mascot girl for the 2005 FIFA Club World Championship and covered the tournament as a special presenter for NTV.

[52] In December 2006, she hosted the 32nd Radio Charity Musicthon and acted as special presenter for NTV's coverage of the 2006 FIFA Club World Cup.

[55] In March 2007, Ueto released "Way to Heaven," her first single in over a year, and made a guest appearance in the eighth-season finale of the TBS drama Wataru Seken wa Oni Bakari.

In an interview with Oricon Style, she revealed that the reason she insisted on not writing her own lyrics until then was because she felt "shy" about "opening herself completely" to her audience.

[63] In August 2008, Ueto became the first actress to ever appear on official postage stamps by releasing an original set with photos taken from her 2007 tour.

[74] Ueto next co-starred with Hayato Ichihara in the Shunji Iwai-produced CG animation film, Baton, created in commemoration of the Port of Yokohama's 150th anniversary.

[76][77] In November 2009, Ueto co-starred with Tetsuya Watari in the Sugako Hashida-written and Fukuko Ishii-produced TV movie, Kekkon.

[78] In 2010, Ueto launched her third and fourth wedding dress collections, starred alongside Kin'ya Kitaōji in the Fuji TV drama Zettai Reido, and made a cameo appearance in Shun Oguri's directorial debut, Surely Someday.

[83] In September 2010, Ueto portrayed blind singer-songwriter Satoko Tatemichi in the TV movie Ai wa Mieru.

[87][88] Boasting advertising contracts with 13 different companies, Ueto was crowned CM Queen for a second consecutive year, making it the fifth time she has held the title.

[90] Ueto was confirmed to appear in the series finale of the long-running drama Wataru Seken wa Oni Bakari, scheduled to air in September 2011.

[6] Ueto dated Japanese singer and actor Gō Morita of the boy band V6 for eight years before splitting in April 2010.

[98] In April 2011, Ueto joined veteran actors Tetsuya Watari and Hiroshi Tachi in handing out food and other relief supplies to disaster victims in the 2011 Tōhoku earthquake and tsunami-stricken area of Ishinomaki in Miyagi.