Objective: To investigate the predictive value of behavioral economic task performance on functional ability in older adults. It was hypothesized that decrements in instrumental activities of daily living (IADLs) would be associated with greater: (1) delay discounting (DD) impulsivity, (2) probability discounting (PD) risk-proneness, and (3) response inconsistency. Method: 64 older adults were recruited from the community (65–85 years, mean age = 76.25, 76.60% female). Exclusionary criteria included history of neurological illness, substance dependency within past 5 years, score of ≤ 20 on the Mini-Mental Status Examination. Discounting tasks were comprised of dichotomous choices between smaller, immediate/guaranteed and larger, and delayed/probabilistic monetary values. Impulsivity and risk-proneness were operationalized as area-under-the-curve (AUC), while response (in)consistency was based on contradictory selections. The Direct Assessment of Functional Status—Revised (DAFS-R) was employed as the performance-based assessment of IADLs. Hierarchical regression analyses evaluated whether discounting performance accounts for variance in IADLs above and beyond relevant variables that significantly correlated with IADLs in our sample, including education level, intellectual functioning, and income. Results: Demographic characteristics were significant predictors of functional ability (p = .001; R2 = .237). Significant additional variance was accounted for by PD AUC (p = .014; ΔR2 = .075), PD response (in)consistency (p = .046; ΔR2 = .050), and DD response (in)consistency (p = .010; ΔR2 = .081). DD AUC did not add significantly (p = .861). Conclusion(s): Discounting risk-proneness and response (in)consistency hold potential to predict functional decline, likely due to the deterioration of relevant brain regions and cognitive abilities.