Béatrice Tillier was born in Lyon. She grew up in the Ardèche, where she developed her passion for nature. Her trips throughout Europe with her grandmother gave her an equal interest in architecture and art. She studied Literature, but completed her education at the Émile Cohl art school in Lyon. Before graduation, she had already illustrated a novel for the publishing house Nathan.
She then did regular work for Éditions Milan, while preparing the comics trilogy 'Fée et Trendres Automates'. Tillier illustrated the first two installments of this science fiction serial, that was written by Téhy and published by Vents d'Ouest in 1996 and 2000. Tillier then drew the World War II drama 'Mon Voisin, le Père Noël', written by Philippe Bonifay and published by Casterman in 2005. In 2008 she teamed up with Jean Dufaux to create another trilogy, 'Le Bois des Vierges', published by Robert Laffont.
Tillier has also contributed to Jean-Pierre Eugène's 2009 anthology 'Souvenirs de Films', published by Le Lombard. She is married to comic artist Olivier Brazao, whom she has assisted on the coloring of the series 'Sheewõwkees'.