Use of allogeneic hematopoietic cell transplantation (alloHCT) is increasing in older patients with hematologic malignancies. Studies suggest that geriatric assessment (GA), incorporating functional measures such as instrumental activities of daily living (IADL), delineates subtle age-related impairments that enhance risk-stratification. The objective of this multi-institutional retrospective study was to evaluate the prognostic utility of GA metrics collected pre-alloHCT. Eligibility criteria included age ≥50 and pre-alloHCT GA inclusive of at least IADL. Beyond IADL, additional geriatric metrics were collected where available and included Medical Outcomes Study Physical Health score (MOS-PH), Timed Up and Go (TUG), and cognition by Blessed Orientation Memory Concentration (BOMC). Three hundred thirty subjects were included, with a median age of 63 (range 50 to 77). Impairments were frequent: 36% had at least 1 IADL impairment; 14% had TUG ≥13.5 seconds; and 17% had cognitive impairment (BOMC ≥ 7). Median MOS-PH score was 80. IADL and age were not significantly associated with nonrelapse mortality (NRM) or overall survival (OS). In multivariate analysis, only impaired cognition and Hematopoietic Cell Transplant-Comorbidity Index score ≥3 showed an independent association with 1-year NRM (subdistribution hazard ratio [SHR], 2.36; P = .01; and SHR, 2.19; P = .009, respectively). Cognitive impairment independently conferred inferior 1-year OS (hazard ratio, 1.94; P = .01). In a preplanned subgroup analysis in 224 patients aged ≥60 years, cognitive impairment remained the sole GA metric predictive of NRM (2-year NRM: SHR, 2.72; P = .007). These data suggest that cognitive impairment elevates risk of post-alloHCT NRM in older patients.