On April 7, 2017, she released her third studio album titled Manu. That same day, the single Hipnose, the lead single of her new album was released. The Manu Tour started on May 18th, in Campinas. In July she made a cameo appearance in the series Planeta B, which was shown at Multishow, playing serial killer Josephine. In August, "Muito Muito" was released, the second single from the album, with the direction and script of the music video made by the singer herself. In November, she publishes her debut book, Olá Caderno!, through the publisher Rocco. In February 2018, she directed the clip of the song "Clareiamô" by duo Anavitória. In March, she released the single "Me Beija", with a music video full of references to the 2000s. In June, she released a single in collaboration with Portuguese singer Agir, a new version of the song "Ninguém Vai Saber", a song that she previously released solo on the album Manu. She was also invited by the singer for a performance of the song at Rock in Rio Lisboa.
Her participation in the reality show, made her book Olá, Caderno! released in 2017, sell out and gain an adaptation in the cinema. In February, Gavassi announced a mini tour named Cute but Psycho Experience. However, due to the COVID-19 pandemic, the tour was postponed to 2021. In April, Gavassi reached the 4th position and became the best positioned Brazilian artist on Billboard's Social 50 Chart. The singer also reached 30th position on Emerging Artists, on the Billboard charts, indicating who is currently on the rise. In May, she released the single "Eu Te Quero" in collaboration with singer Zeeba. The song reached 41st place in the TOP 50 of the most played songs on Spotify Brasil. On May 27, she launched her clothing and accessories collection in collaboration with C&A. In the same month, she re-recorded the "Pipoca e Guaraná" jingle for the Guaraná Antarctica advertising commercial. In June, Gavassi was invited to join the cast of the soap opera Salve-se Quem Puder, but she had to turn down the invitation, since she was already participating in the cast of the series Condom Ladies, scripted by the writer Natália Klein, the recordings are scheduled for September and will be shown on Netflix On August 21st, Gavassi released the new single, "Deve Ser Horrível Dormir Sem Mim" with Gloria Groove.