Background To explore how the clinical impact of heart rate (HR) and heart rate variabilities (HRV) during the initial 24 hours after acute intracerebral hemorrhage (ICH) contribute to worse clinical outcomes. Methods and Results In the ATACH‐2 (Antihypertensive Treatment in Intracerebral Hemorrhage 2) trial, the HR was recorded for every 15 minutes from baseline to 1 hour and hourly during the initial 24 hours post‐randomization. We calculated the following: mean, standard deviation, coefficient of variation, successive variation, and average real variability (ARV). Outcomes were hematoma expansion at 24 hours and unfavorable functional outcome, defined as modified Rankin Scale score 4 to 6 at 90 days. Of the 1000 subjects in ATACH‐2, 994 with available HR data were included in the analyses. Overall, 262 experienced hematoma expansion, and 362 had unfavorable outcomes. Increased mean HR was linearly associated with unfavorable outcome (per 10 bpm increase adjusted odds ratio [aOR], 1.31, 95% CI, 1.14–1.50) but not with hematoma expansion, while HR‐ARV was associated with hematoma expansion (aOR, 1.06, 95% CI, 1.01–1.12) and unfavorable outcome (aOR, 1.07, 95% CI, 1.01–1.3). Every 10‐bpm increase in mean HR increased the probability of unfavorable outcome by 4.3%, while every 1 increase in HR‐ARV increased the probability of hematoma expansion by 1.1% and unfavorable outcome by 1.3%. Conclusions Increased mean HR and HR‐ARV within the initial 24 hours were independently associated with unfavorable outcome in acute ICH. Moreover, HR‐ARV was associated with hematoma expansion at 24 hours. This may have future therapeutic implications to accommodate HR and HRV in acute ICH. Registration URL: https://www.clinicaltrials.gov ; Unique Identifier: NCT01176565.