A journalist by training, Tainá started on TV at the age of 19 as VJ of MTV in Rio Grande do Sul. She also worked as a model, making seasons in Milan, Hong Kong and Bangkok. In 2005 she moved to the city of São Paulo to study theater. In 2007 she debuted in the cinema with the film Cão Sem Dono, for which she was awarded best actress in Brazilian festivals. Shortly thereafter, she debuted on Rede Globo in Eterna Magia. In the cinema, she also joined the cast of films such as Plastic City, As Mothers of Chico Xavier and Tropa de Elite 2.
In 2014, she had one of the greatest moments of her career in the soap opera Em Família. She played a lesbian photographer Marina in love with her girlfriend Clara Fernandes played by Giovanna Antonelli.
On 30 November 2013, Tainá Müller married her husband Henrique Sauer in a simple shamanic wedding ceremony in Mexico. Muller and her husband welcomed their first child in April 2016