She was the daughter of the painter Monserrat Aleix and sister of art gallery owners Maria Teresa (1930-2009) and Montserrat (1936), popularly known in Mexico as Las Pecas. With her sister María Teresa she studied at the Massana School in Barcelona, where they were disciples of Miquel Soldevila y Valls. In 1950 he went with his family to Mexico, for reasons of work of his father, Jesús Pecanins y Fàbregas. She worked for a time as a curator at the Tussó Gallery, owned by her sister Teresa, until 1951 when she married and went to the United States with her husband. In 1961 she returned to Mexico, and in 1964 she founded the Pecanins Gallery with her sisters, first in a building in the Juárez neighborhood, since 1966 in the Zona Rosa, with the idea of supporting the proposals of emerging artists such as Francisco Corzas, Arnold Belkin, Arnaldo Coen, Philip Bragar, Fernando García Ponce, Leonel Góngora, José Muñoz Medina and Maxwell Gordon.

From 1972 to 1976 she opened with her sisters a branch of the Pecanins Gallery in Carrer de la Llibreteria in Barcelona, in order to publicize artists from Mexico in Barcelona and artists from Catalonia in Mexico, being frequented by Latin American artists and writers established in the city such as Gabriel Garcia Marquez, Mario Vargas Llosa, Jose Donoso and Carlos Fuentes.

In 1992 she organized with her sisters at the Palau Robert in Barcelona the exhibition To Mexico: homage from Catalonia to Mexico and in 2008 the exhibition Catalan Painters in Mexico, at the Spanish Cultural Center in Mexico City, where works by Josep Guinovart, Antoni Tapies, Joan Miro, Daniel Argimon y Granell, Joan Hernandez Pijoan, Joan Hernández, Josep Bartoli y Guiu, Antoni Peyri y Maciá, Jordi Bodó, Alberto Gironella, and Arcadi Artís y Espriu.

Anna Maria Pecanins died in a car accident on December 8, 2009, a few months after the death of her twin sister Maria Teresa, who died due to respiratory arrest caused by pulmonary emphysema. A year later, the Pecanins Gallery would permanently close.