Although the economic impact of guaranteed income (GI) (recurring, unconditional, and unrestricted cash transfers intended to supplement the income of participants) is well studied, much less is known about how GI may affect health, especially in the context of high-income countries like the United States and Canada. We searched 5 electronic databases for terms related to “guaranteed income” and “cash transfer” through April 23, 2022. Among 5340 records originally identified, 25 met our inclusion criteria and represented 16 unique GI initiatives. Most included studies used a quantitative approach (n = 22; 88%), were published between 2000 and 2022 (n = 21; 84%), and were conducted in the United States (n = 15; 60%). Health outcomes included maternal and child health (eg, preterm births, breastfeeding initiation), healthcare utilization (eg, hospital admissions), mental health (eg, depression), physical health (eg, body mass index), and behavioral health (eg, substance use). Maternal, infant, and child health were the most highly represented health outcomes. Guaranteed-income initiatives generally had significant positive impacts on health outcomes, especially among the most vulnerable recipients. Data were absent on neighborhood-level health outcomes, chronic and infectious diseases, potential unintended consequences, and long-term impacts of GI on health. Studies on the impact of GI on health suggest GI has the potential to positively affect many, but not all, health outcomes. Rigorous assessment of health outcomes is still needed, and additional health outcomes should be considered in the design and evaluation of GI initiatives.