The environmental safety and risk of transporting degradable microplastics (DMPs) and agrochemicals are being actively studied and evaluated. In this study, the aging of polylactic acid (PLA), polyhydroxyalkanoate (PHA), and poly (butylene adipate-co-terephthalate) (PBAT) DMPs were comprehensively explored under ultraviolet (UV) irradiation. The effects of neonicotinoids (acetamiprid, dinotefuran, and nitenpyram) on the transport of DMPs before and after aging were investigated using column experiments and density-functional theory. PHA exhibited stronger resistance to UV degradation than PLA and PBAT owing to its higher hydrophobicity. During aging, ester groups (C–O) were broken in the DMPs and carbonyl groups (C=O) were formed. The calculated molecular electrostatic potential and localized orbital locator as well as the measured zeta potential, verified that the adsorption of neonicotinoids on the DMPs supplemented their surface charge at lower neonicotinoid concentrations, but effectively shielded it at high concentrations. The promoting effect of UV aging on transport was approximately equal for PLA and PBAT but lower for PHA. With the increasing degree of aging, the inhibitory effect of neonicotinoids on DMP recovery became more pronounced. Neonicotinoids, especially dinotefuran, had the most prominent inhibitory effect on the transport of aged PLA and PBAT, with the recoveries of PLA and PBAT UV-aged for 24 h reduced by 38.63% and 34.18%, respectively. These results indicate that the potential ecological hazards arising from the aging and transport of DMPs in the actual environment deserve further investigation.