Age-related proteinopathies, including Alzheimer’s and Parkinson’s disease, are driven by toxic accumulation of misfolded and intrinsically disordered proteins (IDPs) that overwhelm cellular proteostasis. The proteasome clears these proteins, but its failure in disease remains unclear. We engineered a Caenorhabditis elegans model with a hyperactive 20S proteasome (α3ΔN) for selective 20S activation. α3ΔN markedly enhanced IDP and misfolded protein degradation, reduced oxidative damage, and improved endoplasmic reticulum associated degradation (ERAD). Aggregation prone substrates such as vitellogenins and human alpha-1 antitrypsin (ATZ) were efficiently cleared. Integrated proteomic and transcriptomic analyses reveal systemic adaptations featuring increased protein turnover and oxidative stress resistance independent of superoxide dismutases (SODs). Strikingly, α3ΔN extended lifespan and stress resistance independently of canonical unfolded protein response (UPR) signaling via xbp 1. These findings substantiate a “20S pathway” of proteostasis that directly alleviates protein aggregation and oxidative stress, offering a promising therapeutic angle for neurodegenerative diseases