The need for compatible materials for the preservation of cultural heritage is part of a broader trend which foresees the sustainability of products and respect for the environment and the operators as a priority and an alternative to synthetic products. A pre-Hispanic Mesoamerican tradition involves the use of Opuntia ficus-indica Mill. mucilage as an additive to the plasters and as a binder for the wall paintings. The use of Opuntia mucilage has continued over Mexican history to modern times through traditional construction techniques, being transmitted from generation to generation. The traditional extraction method consists in macerating the cladode parenchyma in water for 24 hours at room temperature in a matrix / water ratio of 1:1. In order to optimize the extraction process, the following factors were considered: biomass/water ratio, maceration time, and variations in pH of the extraction solution. The mucilage was analysed by FTIR. Specimens of lime and hydraulic mortars added with 2.5% mucilage were evaluated before and after artificial weathering for colour change (colorimetry), cohesion (ultrasound measurements), integrity (X-rays) and bioreceptivity response (microbiological tests). In all the bio-mortars, no colour change was detected, as well as no increase in bioreceptivity; rather, the addition of mucilage confers resistance to the engraftment of microorganisms. The internal structure shows better compactness in those bio-mortars added with Opuntia mucilage. These results indicate the Opuntia mucilage -derived from pruning waste- as a good candidate as a sustainable alternative to chemical additives in restoration mortars.