Psychological stress is associated with several long-term consequences, including cognitive decline. Our study examined the relationship between psychological stress levels and subjective cognitive decline (SCD) using cross-sectional data from CDC's Behavioral Risk Factor Surveillance System (BRFSS 2020–2022) for participants aged 45 years and older. Among 881,479 participants, 7.5 % were African American, and 10.7 % reported high psychological stress, with 29 % experiencing SCD. High psychological stress had a 3-fold risk of SCD compared to low psychological stress (OR: 3.3; 95 % CI: 2.8, 4.0). A significant interaction between psychological stress and BMI was found in their association with SCD (p = 0.013). Individuals with high psychological stress and a BMI ≥ 25 had 4.3 times higher SCD risk (OR: 4.3; 95 % CI: 3.9, 4.7) compared to those with low psychological stress and a BMI < 25 (OR: 0.23, 95 % CI: 0.2, 0.3). These results highlight the importance of addressing stress to prevent cognitive decline.