[4] Later in 2001, she offered her services in the Portuguese voice over translation in the Canadian/Chinese animated series Braceface, for the character Sharon Spitz.

[1] She began acting in amateur theater, insisting to her parents invest in her career as an actress, even participating in various advertising campaigns.

[8] When she was thirteen, in 1994, Mariana debuted on television in the telenovela 74.5 - Uma Onda no Ar in Rede Manchete making a cameo appearance to the latter.

[9] Shortly afterwards, she was invited to join the cast of Fascinação of SBT in 1998, where she played the character Emília, her first major television role.

She appeared in the episode "Dupla Traição" in the series Você Decide and in the film Caminho dos Sonhos portraying the character Ruth Stern.

[17] That same year, she also starred in her second film, Dias de Nietzsche em Turim, playing Júlia Fino.

[18] In 2002, Mariana Ximenes made a guest appearance in the comedy series Os Normais,[19] in "A Turma do Didi" as Glorinha and Brava Gente in episode "Arioswaldo e o Lobisomem" as Branca Luz, alongside Suzana Vieira and Ângelo Antônio.

She played Ana, the main protagonist, also known as Aninha, in Chocolate com Pimenta that earned her media attention due to its success thanks to her portrayal in the telenovela.

In the plot, her character is a violinist who inherits 49% of her deceased uncle, Omar (Francisco Cuoco), who owns a fictitious company called Luxus.

[33] After Cobras & Lagartos, she made a cameo appearance in Paraíso Tropical as Sônia, a journalist who becomes the new girlfriend of the character Mateus, played by Gustavo Leão.

[34] Originally, Gilberto Braga had cast her to play the character Bebel, but she later turned down the offer thus Camila Pitanga taking over the role.

In 2010, Mariana Ximenes was cast to play Clara Medeiros in the telenovela Passione, her first villain role in her acting career.

In order to compose the character as well as some other villains in Brazilian telenovelas, such as Nazaré of Renata Sorrah and Maria de Fátima of Glória Pires, some changes were also made on her visual appearance to liven the character, making her hair longer and dressing in bolder outfits.

Besides being a very complex character, who sometimes portrays villainess girl in me she demanded a lot, it was the first time that I collaborated with Tony Ramos, Fernanda Montenegro, Cleyde Yáconis, and Leonardo Villar.

The actress Mariana Ximenes topped the poll site in Caras magazine as the greatest villain in telenovela history.

The journalist Fabíola Reipert said, "Mariana Ximenes can show her talent, because she is in the main cast of the telenovela, even with only 29 years".

[46] Furthermore, Mariana returned to theater, starring in the play Os Altruístas, directed by Guilherme Weber, after nine years of not performing on stage.

[48][49] In May 2012, she was part of the cast of the series As Brasileiras in the episode "A Adormecida de Foz do Iguaçu", playing the seductive character Liliane.

[55] In 2015, she was auditioned for A Regra do Jogo but in March 2015, Rede Globo announced that Vanessa Giácomo was selected for the role.

[96] In 2000, investing in the success of the soap opera Uga-Uga, Rede Globo signed a contract with Estrela for manufacturing a Susi Bionda doll, inspired by the character of Mariana Ximenes.