Peumus boldus, a tree native to Chile, is extensively used for medicinal purposes due to its richness in alkaloids and antioxidant polyphenols. A species of galling insect, Dasineura sp. induces structural and chemical changes on P. boldus stems while its galls are established and developed. Taking into account the antioxidant properties of P. boldus polyphenols, it would be expected that Dasineura sp. induces changes in the accumulation sites, chemical profile, and antioxidant activity of the P. boldus stem polyphenols, related to different reactive oxygen species (ROS) production levels during gall development. Dasineura sp. induces changes in the accumulation sites of total polyphenols, flavonols, and lignin, redirecting their accumulation toward the sites of greatest production of H2O2 and O2.-. Although changes in total polyphenol content would be expected, this did not vary significantly between non-galled and galled stems. However, the galling insect induced changes in the profile and concentration of soluble polyphenols, leading to the gall extracts' antioxidant capacity decreasing significantly during the maturation and senescence stages. Additionally, during the maturation stage, lignin deposition increases in the more peripheral gall tissues, which also contributes to ROS dissipation. The differences in the different gall developmental stages' antioxidant activity could be related to the identity and concentration of phenolic compounds in each gall extract, rather than to the total phenol content. Regardless of the mechanisms involved, the dissipation of the ROS generated by Dasineura sp. activity occurs, restoring the redox balance in galls and guaranteeing the success of the inducer.