The bioprinting characterization dataset documents a comprehensive series of 3D bioprinting experiments aimed at optimizing the fabrication of tumor–endothelium models through systematic variation of bioprinting parameters and hydrogel compositions. The purpose of the dataset is to develop and refine reproducible bioprinted hydrogels that accurately replicate physiological features such as endothelial barrier integrity and cancer cell extravasation within engineered extracellular matrix (ECM) environments. The data encompass multiple experimental trials in which different hydrogel formulations, UV crosslinking conditions, and cell seeding strategies were tested to identify the optimal conditions for construct stability, cell viability, and functional performance. Each experiment is recorded in detail across several time points, from initial cell thawing and ECM preparation to cytokine treatment, TEER (transendothelial electrical resistance) measurements, and immunostaining. The dataset integrates both procedural metadata, such as plate layouts, reagent information, and experimental goals, and assay results, including live/dead viability, diffusion, and permeability analyses. Overall, the dataset represents a structured and iterative effort to optimize bioprinting techniques and biomaterial compositions for fabricating robust, functional 3D microphysiological models that enable the study of cancer cell migration, endothelial responses, and biomaterial–cell interactions in a controlled in vitro system.