<p>Persistent pesticides pose significant environmental and health risks due to their resistance to conventional water treatment methods. This study explores the cooperative oxidation and reduction of two typical pesticides, namely atrazine (ATZ) and lindane (LND), under vacuum ultraviolet (VUV) irradiation, with a particular focus on the dual role of dissolved oxygen (DO) in modulating degradation mechanisms and kinetics. In oxygen-deprived conditions, VUV irradiation achieved 92.9% ATZ removal with minimal TOC reduction (&lt; 5%), whereas the introduction of 10 mg L^–1 DO enhanced ATZ mineralization to 67.1% by sustaining hydroxyl radical (HO^•) concentrations. Conversely, DO presence reduced LND degradation efficiency from 86.5% to 46.6% by scavenging solvated electrons (e_aq^–), yet improved TOC removal from 4.8% to 26.7% through enhanced oxidative transformation of intermediates. ATZ undergoes hydroxyl radical-mediated oxidation, while LND degradation is driven by solvated electrons-initiated reduction. A competition kinetics model was employed to determine the second-order rate constants of reactive species, revealing that HO^• plays a dominant role in ATZ degradation (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({k_{{\text{ATZ,H}}{{\text{O}}^ \bullet }}}\)</EquationSource> </InlineEquation>= 2.5 × 10⁹ M^–1S^–1) and e_aq^– is primarily responsible for LND decomposition (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({k_{{\text{LND,}}{{\text{e}}_{aq}}^{ - }}}\)</EquationSource> </InlineEquation>= 1.0 × 10¹⁰ M^–1S^–1). Numerous degradation byproducts were identified by GC-MS, revealing three pathways for ATZ and multiple reductive routes for LND. These findings highlight the intricate interplay between oxidative and reductive mechanisms mediated by DO, emphasizing the necessity of controlling oxygen levels for efficient pollutant degradation and comprehensive mineralization.</p>