Eliminating and controlling fungal biodeterioration is one of the most important challenges of easel painting conservation. Historically, the pathologies produced by biodeterioration agents had been treated with non-specific products or with biocides specially designed for conservation but risky for human health or the environment due to their toxicity. In recent years, the number of research that studied more respectful solutions for the disinfection of paintings has increased, contributing to society’s efforts to achieve the Sustainable Development Goals (SDGs). Here, an overview of the biodeterioration issues of the easel paintings is presented, critically analyzing chemical and eco-sustainable approaches to prevent or eradicate biodeterioration. Concretely, Essential Oils and light radiations are studied in comparison with the most used chemical biocides in the field, including acids, alcohols, and quaternary ammonium salts. This review describes those strategies’ biocidal mechanisms, efficiency, and reported applications in vitro assays on plates, mockups, and real scale. Benefits and drawbacks are evaluated, including workability, easel painting material alterations, health risks, and environmental sustainability. This review shows innovative and eco-friendly methods from an easel painting conservation perspective, detecting its challenges and opportunities to develop biocontrol strategies to substitute traditional chemical products.