Zucchini is one of the most cultivated and consumed vegetables in the world and often requires pesticide treatment. In this context, a simple and straightforward method for determining pesticide residues in zucchini was proposed based on an effective QuEChERS extraction approach followed by dilution of the unclean extract and analysis by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). During the development of the sample preparation step, the cleanup of the extract using dispersive solid-phase extraction with different sorbents was compared with the analysis of unclean extract. Different dilution rates of the raw extract with ultrapure water were evaluated, and a dilution of 5 times presented adequate analysis performance, minimizing the matrix effect. The established method was suitable for 99 pesticides presenting satisfactory results for trueness, with recoveries ranging from 70 to 120% and precision in terms of relative standard deviations (RSD) ≤ 20%. Practical method limit of quantification ranged from 0.005 to 0.010 mg kg− 1 for all compounds. The method was successfully applied to 20 commercial samples of zucchini, and 15 samples showed the presence of 12 different pesticides, especially the insecticide imidacloprid. The method proved to be simple and effective for routine analysis.