Her audition involved a three-day training camp where participants were expected to learn a new song, a dance routine and a script.

[3] Her debut with the group was on their single "Mr. Moonlight: Ai no Big Band", and her first appearance on a Morning Musume full-length release was their fourth studio album, 4th Ikimasshoi!.

In 2006, Takahashi played the lead role, Sapphire, in Ribon no Kishi The Musical which was a collaboration work by Hello!

The musical was based on Tezuka Osamu's manga and starred v-u-den, Nozomi Tsuji, Aya Matsuura and Natsumi Abe as well as Marcia and Kaoru Ebira of the Takarazuka Revue.

[3] It was announced in July 2008 that Takahashi and fellow Morning Musume member Risa Niigaki would play the 80s J-Pop duo Pink Lady in the TV Drama Hitmaker Aku Yuu Monogatari.

On February 1, 2009, during the "Hello Pro Award '09 ~Elder Club Sotsugyō Kinen Special~" concert held at Yokohama Arena, Yuko Nakazawa passed on her leadership position in Hello!

On January 9, 2011, it was announced that Takahashi would graduate from Morning Musume at the end of the fall tour that year.

[9] Takahashi's last single with Morning Musume, the double A-side "Kono Chikyuu no Heiwa wo Honki de Negatterun dayo!/ Kare to Issho ni Omise ga Shitai" (この地球の平和を本気で願ってるんだよ！/彼と一緒にお店がしたい！), included a B-side solo by Takahashi, "Jishin Motte Yume o Motte Tobitatsu Kara" (自信持って 夢を持って 飛び立つから), and was released on her birthday, September 14.

It was announced that Takahashi would voice a character in the hit anime series Detective Conan, with her episodes airing in early 2013.

Project Fanclub News announced that Takahashi would star in a stage play titled Moshimo Kokumin ga Shusho o Erandara along with Rika Ishikawa, S/mileage members Ayaka Wada and Kanon Fukuda, and Juice=Juice members Karin Miyamoto and Akari Uemura.

On September 10, HMV announced that Takahashi would be releasing her first style book on October 18, titled "AI am I", which would include an interview about her Morning Musume days, as well as her ideas about love.

Takahashi became a regular on the new TV drama Jikken Keiji Totori 2, which began airing on October 12.

In November, Takahashi was cast as Beth Spencer in the musical Merrily We Roll Along, She also played Julia in The Wedding Singer.

2016In spring 2016, Takahashi starred in Hoshi Boshi no Yakusoku, Japan's first live-action film made for a Fulldome Cinema, which was screened in her hometown's Fukui City Museum of Natural History Dome Theater.

Takahashi and Abe held a reception on January 22, 2015, with Morning Musume members Kei Yasuda, Rika Ishikawa, Hitomi Yoshizawa, Makoto Ogawa, Asami Konno, Miki Fujimoto, Mizuki Fukumura, Erina Ikuta, and Riho Sayashi, along with many others, in attendance.