Updated project metadata. Senescent cells within tumors and their stroma exert complex pro- and anti-tumorigenic functions, yet the potential for targeting such senescent cells for improved therapy remains largely unknown. Here, we uncover the presence of a senescent subset of cancer-associated fibroblasts (CAFs) within pancreatic ductal adenocarcinomas (PDAC) and in premalignant lesions in mice and humans. Senescent CAFs represented different previously-defined CAF subtypes. Senescent CAFs isolated from mouse and humans expressed elevated levels of immunoregulatory genes. Depletion of senescent CAFs, either genetically or using the Bcl-2 inhibitor ABT-199 (venetoclax), increased the proportion of activated CD8+ T cells in mouse pancreatic carcinomas, whereas induction of CAF senescence had the opposite effect. Combining ABT-199 with an immune checkpoint therapy regimen significantly reduced mouse tumor burden. These results indicate that senescent CAFs in PDAC stroma limit the numbers of activated cytotoxic CD8+ T cells, and suggest that their targeted elimination through senolytic treatment may enhance immunotherapy.