Introduction. Sexual and gender minority young adults (SGMYA) face heightened risk of suicidal ideation compared to their heterosexual, cisgender peers. Previous research, relying on retrospective, cross-sectional data, is limited due to recall bias and an inability to capture short-term fluctuations in suicidal thoughts. Recent surges in anti-SGM legislation in the US have led to increased negative news media coverage, but the extent to which this is associated with SGMYA suicide risk is unknown. Using ecological momentary assessment (EMA), this study examines the real-time impact of negative news media exposure on suicidal ideation intensity among SGMYA in Tennessee, a high-stigma US state. Methods. We enrolled 31 SGMYA aged 18-24 with recent suicidal ideation into a smartphone-based EMA study where they completed assessments 3x per day for 28 days. At each assessment, in reference to the time since the last survey, participants reported exposure to SGM and general negative news media (e.g., a news headline) and expectations of identity-based rejection. Participants reported current intensity of active, passive, and self-harm ideation. Statistical analyses employed multilevel modeling. First, we examined within-person relationships among exposure to negative news media and fluctuations in suicidal ideation intensity. Second, we examined the mediating role of expectations of identity-based rejection. Results. The 31 SGMYA participants completed 2189 assessments over the 28-day study period, reflecting an 84.1% EMA compliance rate (range=41.7-100.0%). Participants experienced heightened active, passive, and self-harm ideation at assessments when they were recently exposed to SGM – but not general – negative news media. Multi-level structural equation models demonstrated that expectations of identity-based rejection mediated associations between SGM negative news media exposure and active and passive suicidal ideation intensity. Discussion. This is the first study to report near-real-time relationships among exposure to news media, expectations of rejection, and suicidal ideation. Exposure to SGM negative news media is a proximal risk factor for real-time suicidal ideation intensity via expectations of identity-based rejection. This research underscores the suicidogenic impact of negative news exposure in the daily lives of SGMYA, with intervention implications related to media reporting, policy, and clinical intervention.