Multi-target pharmacology of small molecule cancer drugs significantly contributes to their mechanism of action, side effects, emergence of drug resistance, and opens ways to repurpose, combine or customize drug therapy. In most cases the set of targets affected at therapeutic concentrations is not fully characterized and/or the interaction efficacy values are not accurately quantified. We collected information about multiple targets for each cancer drug along with their experimental effective concentrations or binding activities from multiple sources. All multi-target activity values for each drug then were used to build two proximity network pharmacology maps of anti-cancer drugs and targets of those drugs, respectively. Together with the network map, we showed that the majority of the cancer drugs had substantial multi-target pharmacology based on our current knowledge. In addition, most of the cancer drugs simultaneously affect macromolecular targets from different classes and types. The target subset can further be accentuated and personalized by patient sample specific expression data. The network maps of cancer drugs and targets, as well as all quantified activity data were integrated into a freely available database, CancerDrugMap (http://ruben.ucsd.edu/dnet/maps/drugnet.html). The identified multi-target pharmacology of cancer drugs is essential for improving the efficacy of individually prescribed drugs and drug combinations and minimization of adverse effects.