The use of traditional biocidal products in cultural heritage has suffered a slowdown due to the risks related to human health and the environment. Thus, many studies have been carried out with the aim of testing innovative and environmentally friendly alternatives. In this framework, this review attempts to provide an overview of some novel potential products with biocidal action, tested to counteract the process of degradation of paper and stone materials due to microbial activity, keeping in mind the sustainability criteria. In particular, we have focused our attention on the testing of nanotechnologies, essential oils, DES (deep eutectic solvents) with low toxicity, and colloidal substances for conservation purposes.