We calculate the electromagnetic (charge, magnetic, and quadrupole) form factors and the associated static moments of heavy quarkonia (charmonia and bottomonia) using the basis light front quantization (BLFQ) approach. For this work, we adopt light front wave functions (LFWFs) generated by a holographic QCD confining potential and a one-gluon exchange interaction with fixed coupling. We compare our BLFQ results with the limiting case of a single BLFQ basis state description of heavy quarkonia and with other available results. These comparisons provide insights into relativistic effects. Using the same LFWFs generated in the BLFQ approach, we also present the generalized parton distributions (GPDs) for selected mesons including those for radially excited mesons such as ψ′ and ϒ′. Our GPD results establish the foundation within BLFQ for further investigating hadronic structure such as probing the spin structure of spin-one hadrons in the off-forward limit.