Ready-to-eat vegetables have been rising in popularity due to new trends in diet and lifestyle, thus impacting commercial and domestic environments. Production systems sometimes need the aid of pesticides to achieve their goals and protect their crops, while also maintaining food safety. Different cleaning strategies are used for this reason; therefore, there is a need to analyze their effects regarding the amount of pesticide residues. Wanting to test the differences between several cleaning procedures used for ready-to-eat vegetables, ultrasound baths and cleaning solutions were studied. To achieve this goal, lettuce plants were grown in controlled conditions to obtain a homogenous batch, these plants were fumigated with chlorpyrifos methyl, pirimicarb, imidacloprid, boscalid and pyraclostrobin. After harvest, four plants were treated with four solutions, running water, sodium hypochlorite (100 ppm), peracetic acid (80 ppm) and acetic acid (4%). The other 60 plants were placed in ultrasound baths at 25, 37, 45 or 80 kHz for 10 or 15 minutes. An acetate QuEChERS method was validated to analyze pesticide residues through a HPLC-MS/MS system. The results showed that all decontamination procedures managed to reduce the amount of the applied pesticides, but there were no significant differences among each other. The validated method was also applied to 22 commercial samples, where seven showed pesticide residues beneath the maximum residue levels from Codex Alimentarius while two, out of those seven, exceeded the limit for iprodione according to the European Union.