Through introduction of antigenic materials into hosts, vaccines can elicit adaptive immunity which confers protection to the hosts from subsequent exposure to pathogens and cancerous cells. As active immunizations require immune-competent hosts, passive immunotherapy can be a complementary treatment in which protective biologics are directly administered for more immediate protection. However, GMP production of both vaccines and immuno-therapies can be costly and time-consuming, impeding translation and deployment of promising therapeutic candidates. Prior work has demonstrated the use of synthetic DNA and adaptive electroporation (EP) for in vivo delivery of vaccines and immunoglobulins. In this dissertation, I explored the use of synthetic DNA/EP for in vivo folding, assembly, and secretion of more complex anti-HIV-1 biologic eCD4-Ig, and simultaneous delivery of four distinct HIV bNAbs in a single host. Prolonged expression of both eCD4-Ig and HIV bNAbs were observed, demonstrating the host’s own myocytes can be efficient bio-factories for the assembly of biologics. In the case of eCD4-Ig, the neutralization potency can be improved when the biologic is post-translationally modified in vivo through a co-administered DNA-encoded enzyme. Harnessing engineering lessons learnt for in vivo expression of complex protein domains, I studied if DNA/EP can be used to launch designed self-assembly nanoparticle vaccines in vivo. Using three complementary techniques, I directly demonstrated that DNA-launched HIV-1 priming antigen eOD-GT8-60mer can assemble in vivo and can induce significantly faster sero-conversion, higher setpoint antibody titers and CD8+ T-cell responses (CTL) in both mice and guinea pigs than a DNA-encoded GT8-monomer. Importantly, induction of CTL was unique to DNA-launched nano-vaccines and not observed for protein nano-vaccines, due to differences I observed regarding the mechanisms of antigen presentations for each. This observation was used to construct the next-generation DNA-launched nano-vaccines scaffolding melanoma tumor-associated antigens, which exerted strong protection to mice challenged with B16F10 melanoma cells. In summary, my work has demonstrated that DNA/EP can be a robust mechanism through which complex biologics and vaccines can be delivered to induce unique immunological features highly relevant in the treatment of cancer and other diseases and provide new tools for study for the betterment of human and animal health.