Wildfire smoke is a growing public health concern in the United States. Numerous studies have documented associations between ambient smoke exposure and severe patient outcomes for single fire seasons or limited geographic regions. However, there are few national‐scale health studies of wildfire smoke in the U.S., few studies investigating Intensive Care Unit (ICU) admissions as an outcome, and few specifically framed around hospital operations. This study retrospectively examined the associations between ambient wildfire‐related PM2.5 at a hospital ZIP code with total hospital ICU admissions using a national‐scale hospitalization data set. Wildfire smoke was characterized using a combination of kriged PM2.5 monitor observations and satellite‐derived plume polygons from NOAA’s Hazard Mapping System. ICU admissions data were acquired from Premier, Inc. and encompass 15‐20% of all U.S. ICU admissions during the study period. Associations were estimated using a distributed‐lag conditional Poisson model under a time‐stratified case‐crossover design. We found that a 10 μg/m3 increase in daily wildfire PM2.5 was associated with a 2.7% (95% CI: 1.3, 4.1; p=0.00018) increase in ICU admissions five days later. Following a simulated severe 7‐day 120 μg/m3 smoke event, our results predict ICU bed utilization peaking at 131% (95% CI: 43, 239; p<10‐5) over baseline. Under stratification, positive associations were found among patients aged 0‐20 and 60+, patients living in the Midwest Census Region, patients admitted in the years 2013‐2015, and non‐Black patients, though other results were mixed. Our work suggests that hospitals may need to pre‐position vital critical care resources when severe smoke events are forecast.