Marine sponges have been implicated in biomonitoring and bioremediation of various pollutants, several of which are recalcitrant contaminants of concern. The filter-feeding nature of sponges results in the entrapment of contaminants, including pathogens, heavy metals, and microplastics. Several studies have demonstrated the ability of sponges to retain pollutants and implicated both sponges and members of the sponge microbiome in their digestion, transformation, or degradation. Despite this, the mechanisms by which the sponge holobiont accumulates and detoxifies pollutants are not well understood. Additionally, no large-scale sponge-centered bioremediation trials have been conducted. In this chapter, we explore the potential use of marine sponges as tools for bioremediation of biological and chemical pollutants that pose significant threats to the health of humans, animals in aquaculture, and the environment.