Heterogeneous photocatalysis exhibits the potential for the complete degradation of pollutants present in water or gas phase. The effective realization of heterogeneous photocatalysis, at both large-scale industrial setups for water treatment and in situ application for solar remediation of ecological units, can be achieved by the concurrent development of photocatalytic supports along with solid semiconductor materials targeted for implementation as photocatalysts. This chapter provides an update of such developments in the field of photocatalytic supports, very specifically, on cellular solid-based carriers (foams). In the first part, a brief introduction to the fundamentals of cellular solids is presented. Subsequently, the role of cellular solids, as structured photocatalytic supports, for implementation in large-scale, continuously processed photoreactors for high-throughput water treatment, are discussed. The second part of this chapter reports all the materials used, up-to-date, in the fabrication of cellular solid-based photocatalyst carriers for the real-time solar remediation of the natural system. Finally, this chapter ends up in the discussion of novel cellulose nanofiber-based nanofoams as buoyant photocatalytic supports for the realization of bio-based, nonmetallic, nontoxic floating photocatalysts.