Later, in 2007, she debuted as a voice actress and singer after passing an audition held by the music company Victor Entertainment; she was then cast as the character Ranka Lee in the 2008 anime series Macross Frontier.

Her songs have been featured in series such as Kämpfer, Tamayura, Kotoura-san, Lagrange: The Flower of Rin-ne, and Ascendance of a Bookworm.

[11] She ended up being the audition's winner,[12] which would lead to her being cast as the speaking and singing voice of the character Ranka Lee.

[8] Nakajima made her debut performance as a professional artist at the "Macross 25th Anniversary Concert" on April 18, 2007, as she had been cast as the character Ranka Lee.

[26] This was followed by the release of the single "Kamisama no Itazura" (神様のいたずら) on October 26, 2011; the title song is used as the ending theme to the anime series Tamayura: Hitotose.

was released on February 2, 2012; "Try Unite" was used as the opening theme to the anime series Lagrange: The Flower of Rin-ne.

[32] On December 2, 2013, Stardust Promotion announced that Nakajima would go on an indefinite hiatus from her music career after the release of her third album Thank You on February 26, 2014[33] and a final concert on March 20, 2014, although she would continue to be active in the voice-acting industry.

She responded that she felt that had few expectations about herself, and she was worried that she had become so associated with the role of Ranka that she would be unable to establish an identity as "Megumi Nakajima".

Once the films had finished release, she realized that she had already been a voice actor for three years, and yet felt that her roles did not suit her, even feeling that her confidence was low despite being treated kindly by her peers.

[36] On December 1, 2016, Nakajima's management announced that she would return from her hiatus to perform the song "Watashi no Sekai", which is used as the ending theme to the 2017 anime television series Fuuka.

[37] Her second post-comeback single "Saturday Night Question" was released on November 6, 2017; the title song is used as the opening theme to the anime series Recovery of an MMO Junkie.

[41] In August 2018, she performed at C3 AFA Indonesia in Jakarta,[42] the last to be held in the country prior to the event's discontinuation.

[46] She released a compilation album titled 30 Pieces of Love on her 30th birthday, June 5, 2019;[47] the limited edition includes a Blu-ray disc featuring a video shot in the Philippines, and a cover of the Filipino song "Kailan".

[53] During Nakajima's musical hiatus, she continued playing roles in anime series and other franchises, most notably Cure Lovely in HappinessCharge PreCure!

[54] Following her return to music, she would then play the roles of Charlotte Abelfreyja Drossel in Violet Evergarden,[55] Maiko Osonoi in Miss Caretaker of Sunohara-sou,[56] and Dolphin Mii in Saint Seiya: Saintia Shō.

[59] Nakajima cites growing up in a family that appreciated music as one of the factors that made her decide to pursue a singing career.

She noted that she initially had a complex with her voice and felt that it was "lacking in personality", which made her reluctant to talk too much.