Proteolysis targeting chimeras (PROTACs), a class of targeted protein degraders, are advancing in clinical development, necessitating the accurate prediction of human pharmacokinetics (PK). This study developed a physiologically based pharmacokinetic (PBPK) modeling approach informed by in vitro to in vivo extrapolation to predict the human PK of 2 PROTACs: vepdegestrant (ARV-471) and bavdegalutamide (ARV-110). Bottom-up PBPK models were built in mouse (ARV-471), and in mouse, rat, and dog (ARV-110) using physicochemical and in vitro absorption, distribution, metabolism, and excretion data, including solubility, permeability from a modified Genentech Madin-Darby canine kidney cells assay with 4% bovine serum albumin, and liver microsomal intrinsic clearance (CL). In vitro to in vivo extrapolation gaps were identified and addressed using empirical scalars, including additional systemic CL and tissue partition coefficient scalars, to capture observed intravenous PK. Oral absorption and exposure in preclinical species were predicted using a mechanistic absorption model, assuming passive diffusion driven by total drug concentration. Based on the preclinical PBPK strategy, predicted human apparent CL after oral administration and apparent volume of distribution after oral dosing values for ARV-110 at 35 mg aligned within 2-fold of clinical observations. For ARV-471 at 30 mg oral dose, apparent volume of distribution after oral dosing predictions were within range, but apparent CL after oral administration was overpredicted. To improve alignment with the observed clinical PK, model refinement was limited to adjusting the additional systemic CL scalar, whereas absorption and distribution parameters remained unchanged. The refined PBPK models successfully simulated human oral PK within 2-fold of observed values across multiple doses (60-360 mg for ARV-471 and 70-140 mg for ARV-110). This PBPK modeling framework may support human PK prediction of PROTACs during late-stage drug discovery and development. SIGNIFICANCE STATEMENT: This study highlights that a physiologically based pharmacokinetic (PK)-in vitro to in vivo extrapolation strategy can reliably predict the human PK of proteolysis targeting chimeras, an emerging therapeutic class with complex absorption, distribution, metabolism, and excretion properties. Incorporating mechanistic absorption modeling and permeability data from modified in vitro assays (Genentech Madin-Darby canine kidney cells with 4% bovine serum albumin) improved oral absorption predictions, whereas the integration of multispecies preclinical PK data enhanced the translational accuracy of human PK predictions. Together, these findings establish a translational physiologically based PK framework for estimating oral exposure in first-in-human studies and supporting model-informed development of proteolysis targeting chimeras drug candidates.