This study presents a validated multiresidue analytical method for the determination of 821 pesticides in cucumber using both LC-MS/MS and GC-MS/MS, following the QuEChERS extraction protocol. Method validation was carried out in accordance with the Saudi Food and Drug Authority (SFDA) guidelines.   Key validation parameters included matrix effect, linearity, recovery, and precision.  Precision was evaluated through six replicate injections of a 10 microgram/L pesticide mixture.  The relative standard deviation (RSD) of peak areas was below 20% for 513 compounds analyzed by LC-MS/MS and 308 compounds by GC-MS/MS.  Specificity of the method was confirmed by analyzing six different blank samples (both reagent and matrix blanks), with no significant interference observed at the reporting level of 10 microgram/L.  Calibration curves demonstrated excellent linearity over the range of 1-75 micrograms/L for LC-MS/MS and 5-100 micrograms/L for GC-MS/MS, with all calibration points meeting the accuracy acceptance range of 80-120%. To enhance extraction efficiency, and additional 10mL of water was added during the extraction step alongside acetonitrile, which resulted in significantly improved recovery rates.  Trueness of the method was verified using spiked samples at 10, 20, and 50 micrograms/kg for LC-MS/MS and 10 and 20 micrograms/kg for GC-MS/MS, each in six replicates.  Mean recoveries for most analytes ranged from 70% to 120%, in compliance with method accuracy criteria.  According to SFDA requirements, all target compounds showed reproducibility at their respective limits of quantification (LOQs), with RSD values below 20%, confirming the method's accuracy and precision for routine monitoring.