Nanographenes, such as graphene quantum dots (GQDs) and nanoribbons (GNRs), are lightharvesting chromophores that exhibit desirable excitonic properties for application in photocatalysis. The relative size of GQDs and GNRs constrain their excitons to a size that is smaller than the essentially infinitely large exciton Bohr radius of bulk graphene. Consequentially, excitons in these systems are quantum-confined, enabling size tunable energy gaps. Size-dependent tunability of the energy gap has been shown both theoretically and experimentally, demonstrating the versatility of light-harvesting in nanographenes. For example, triangular GQDs of varying size exhibit a progressive redshift of their ultranarrow absorption and emission bands with increasing size. Nanographene size/shape can also be utilized to tune their optical properties (and chemical stability) and is best described by the chemically intuitive Clar's sextet rule of polycyclic aromatic hydrocarbons which states that the more aromatic sextets (that is, the more benzene-like subunits) in the molecule, the larger the optical gap and higher the stability. Computational results confirm the sextet rule when comparing armchairand zigzag-edged nanographenes. Zigzag derivatives contain more nodes and less sextets than their armchair analogs, which results in the destabilization of their HOMO levels and a narrowing of their energy gaps. Chemical functionalization with electron-donating groups have also been used to systematically engineer the energy gap of GQDs for application in photocatalytic water splitting and CO2 reduction. These photocatalytic reactions have also been demonstrated for GQDs used in 0D/2D van der Waals heterojunctions with graphene. GQDs can also self-assemble into π-stacked structures that efficiently harvest light along the stack . Furthermore, the photocatalytic properties of GQDs are enhanced upon coordination of a metal catalyst, such as cobaloximes for hydrogen evolution chemistry. Unlike GQDs, application of GNRs remains relatively unexplored, yet these compounds show great potential in photocatalysis since their absorption profiles cover much of the visible light region, making them efficient solar light absorbers. In addition to their excellent light harvesting, GNRs exhibit high charge carrier mobilities which are expected to enable efficient delivery of charge carriers to the oxidation and reduction catalytic sites for photocatalysis.