Monoclonal antibodies (mAbs) have emerged over the last 20 years as an invaluable biosensing, diagnostic, and therapeutic tool for targeting cancer. With their tight antigen binding and specificity, mAbs are a modular platform for a host of therapeutic modalities, most recently in bioconjugates. Bioconjugates are broadly defined as biological targeting moieties covalently linked with therapeutic molecules and are useful in targeting potent therapeutics to specific cells and tissues. In this work, we develop and investigate mAb bioconjugates for targeted delivery of small molecules, nucleic acids, peptides, and proteins. First, we establish methods for in-house expression, purification, and characterization of mAbs that undergo lysosomal and fast recycling endocytosis pathways upon binding to a target antigen. We then utilize biorthogonal reaction pairs to append various cargo to the mAbs. With an eye toward short-interfering RNA (siRNA) delivery, we conjugate siRNA and membrane disrupting agents to antibodies for co-delivery, targeted cytosolic localization, and gene knockdown of a luciferase reporter gene. Finally, we engineer antibodies with two, orthogonal conjugation sites and to attach sequentially cleavable cargos to a single mAb. With this, we demonstrate controlled, site-specific, dual-labeled antibodies with extracellular and intracellular cargo release mechanisms that can be implicated for sequential release antibody drug conjugates (ADCs).