2009–2011: Breakthrough and Manu Gavassi
She began her career in magazine Capricho's staff. She participated in Galera Capricho, a select group of girls who wrote about beauty products and various other issues of teenage years. In her entry form she had mentioned that she liked to sing, so a Capricho employee soon claimed that she should post a video singing. In the meantime, she began to cover songs from Justin Bieber and Taylor Swift, and also sang songs of her own, uploading them on her YouTube channel, until her father, who worked on the Jovem Pan FM radio, sent a demo of hers to producer Rick Bonadio, who called the artist to meet him at his record label and record her first studio album.
Soon after, Gavassi began working on the album, which was recorded in two months and released on August 31, 2010. The first single, Garoto Errado, was made available a week before the album's release. The music video for the song garnered more than 38 million views on YouTube, with guest appearance of the winner of Colírios Capricho, Renan Grassi, and ex-contestans Bruno Anacleto and Mateus Emmerich. Two more songs from the album were released as well: Pode Falar and Planos Impossíveis. The first show to promote the album happened on September 18, 2010, at the NoCapricho 2010 event.
Capricho magazine created for a blog for the artist and a web-series of five episodes, showing the backstage of her life. The episodes reached more than 300,000 views each. In addition, she was cover for the edition 1106 of the magazine. She also participated in the premiere of Radio Disney in Brazil. Gavassi also opened concertes for Isa TKM's Isa Forever Tour on April 15, 16 and 17 in São Paulo and Rio de Janeiro.
In 2011, the single Garoto Errado was on the soundtrack of Rebelde, RecordTV's telenovela. On November 15, 2011, Gavassi released her new song, "Odeio," which is featured in the deluxe edition of her self-titled debut album. At the end of the same year she opened concerts for Rebeldes' first tour.
2012–2014: Clichê Adolescente and acting
On September 17, 2012, Gavassi released a comeback single to announce her second studio album, Conto de Fadas (Fairy Tale). The song reached the top position in 16 hours after its release. It features excerpts from conversations with Di Ferrero, lead singer of rock band NX Zero. On April 21, 2013, she released on iTunes the first single from her second studio album, titled Clichê Adolescente (Teenage Cliche). On May 13, 2013, she released on her Facebook page the third single, called Cicatriz (Scar). The album "Clichê Adolescente" was released November 29, 2013. Earlier in August 2013, she made a duet with Mexican singer Dulce María in Antes Que Ver el Sol. In 2014 she debuted as an actress in the novel Em Família. At the end of 2014 he began to play the villain Vick of the twenty-second season of Malhação. On December 5, 2014, he released the music video for "That Love So Wrong," recorded in Los Angeles and featured in the Young Evening collection.
2015–2016: Vício, cinema career, new record label
After taking a break as a singer to further develop her work as an actress, Gavassi announced that she was recording an extended play titled Vício (Addiction), which featured five previously unreleased tracks. Shortly after, she signed contract with Angará Music label, leaving Midas Music after five years. The first single, Camiseta was released on November 13. On December 11, 2015 the extended play Vício was released, peaked at number 2 on iTunes Brazil. The whole album was produced by Junior Lima. The second single, Direção was released in early January 2016. Soon after the release of the EP, the singer announced that she would go on the Vicío Tour, taking off in March 2016. In November, Gavassi confirmed that she was recording a feature film titled "Socorro, Virei Uma Garota", scheduled for 2017. In December 2016, she signed a contract with Universal Music, continuing the recording of her third studio album.
2017–present: MANU and book
In early 2017, Manu recorded new songs for her third album said she had finalized her book. On April 7, 2017, she released "Hipnose" lead single from MANU, her new work. The tour of the album began on May 18, 2017 in Campinas. "Muito Muito" was released as the album's second single in August 2017. On March 30, Manu released "Me Beija", one of Manu's tracks as a single along with a clip full of references to the 2000s. In November 2017, Manu launched through the Rocco publishing house his debut book, a teenage novel entitled Olá, Caderno!. In July 2018, lived the character Pamela Toledo, one of the protagonists in the series Z4. In December, he released the EP Cute But Psycho, with three unreleased tracks along with a photo essay. In the same month, she launched a web series based on her life called Garota Errada on her YouTube channel. In May 2019 was released the MINIDOCs Nashville EP with 4 tracks of re-readings of some of his hits. Recorded in Nashville, the EP ranked first in iTunes Brazil.