Immunotherapy has expanded the therapeutic landscape for advanced cancers, including solid tumors and lymphomas. For many patients with cancer, these agents have been shown to have substantial efficacy and favorable toxicity compared with cytotoxic agents, particularly in the second-line setting. With the advent of anti-PD-1 and anti-PD-L1 checkpoint inhibitors, combination immunotherapy- and chemoimmunotherapy-based strategies have emerged as promising novel regimens to improve cancer-related outcomes. Older adults age 65 or older represent the growing majority of patients diagnosed with cancer. However, older adults are under-represented in clinical trials in general, as well as in the landmark studies that led to approval of these immunotherapy agents. Because of increasing age and attendant multimorbidity and impaired functional status, many of these patients seen in the community-based oncology practices would not have been considered eligible for such studies. Thus, the results of these studies are difficult to generalize to a broader patient population with these competing risks. Furthermore, robust evaluation of toxicities, effect on quality of life and functional status, and aging-related (i.e., immunosenescence) and immunotherapy-related changes affecting the immune system remain underexplored research areas for older adults. This review examines the role of immunotherapy and its unique issues, specifically in older adults with lung cancer, bladder cancer, and lymphomas.