Abstract CD8+ T cells are critical for the immune response to pathogens and tumors, and CD8+ T cell memory protects against repeat infections. In this study, we identify the activating transcription factor 7 interacting protein (ATF7ip) as a critical regulator of CD8+ T cell immune responses. Mice with a T cell–specific deletion of ATF7ip have a CD8+ T cell–intrinsic enhancement of Il7r expression and Il2 expression leading to enhanced effector and memory responses. Chromatin immunoprecipitation sequencing studies identified ATF7ip as a repressor of Il7r and Il2 gene expression through the deposition of the repressive histone mark H3K9me3 at the Il7r gene and Il2–Il21 intergenic region. Interestingly, ATF7ip targeted transposable elements for H3K9me3 deposition at both the IL7r locus and the Il2–Il21 intergenic region, indicating that ATF7ip silencing of transposable elements is important for regulating CD8+ T cell function. These results demonstrate a new epigenetic pathway by which IL-7R and IL-2 production are constrained in CD8+ T cells, and this may open up new avenues for modulating their production.