A novel magnetic blade spray-tandem mass spectrometry (MBS-MS/MS) assay was developed and optimized, and its performance was characterized for the analysis of 204 pesticides from wastewater treatment facility (WWTF) process water. These results were compared and experimentally validated with an untargeted, high-resolution MS (HRMS) approach that employed liquid chromatography (LC)-amenable thin-film microextraction (TFME) devices to further elucidate the fate of pesticides through the WWTF process. As a result of our optimizations, we report an optimized workflow with an extraction time of 10 min, 150 μg of magnetic HLB particles, and 5 s of desorption. Excellent linearity was obtained for 168 of the 204 pesticides in deionized water, where 90% of the quantifiable pesticides had a determination coefficient (R2) of 0.99 across 3 orders of magnitude and 80% had limits of quantification below 0.5 ng/mL. We subsequently applied our optimized MBS-MS/MS method for the analysis of samples collected during the various stages of wastewater treatment from two WWTFs in Southern Ontario. This article presents a new streamlined methodology with a fast turnaround time for analyzing a large panel of pesticides, ultimately providing us the opportunity to evaluate the performance of two WWTFs for their efficacy in removing these toxic chemicals.