The purpose of this study was to determine the validity of the 6-min arm ergometry test (6MAT) in predicting peak oxygen consumption (V̇O2peak) in individuals with chronic spinal cord injury (SCI). Fifty-two individuals with chronic SCI (age, 38 ± 10 years; American Spinal Injury Association Impairment Scale (AIS), A-D; neurological level of injury (NLI), C1-L2; years post-injury (YPI), 13 ± 10 years) completed an incremental arm ergometry V̇O2peak test and a submaximal 6MAT. Oxygen consumption (V̇O2) data from both tests were used to create a predictive equation with regression analysis. Subsequently, a cross-validation group comprising an additional 10 individuals with SCI (age, 39 ± 13 years; AIS, A-D; NLI, C3-L3; YPI, 9 ± 9 years) were used to determine the predictive power of the equation. All participants were able to complete both the V̇O2peak and 6MAT assessments. Regression analysis yielded the following equation to predict V̇O2peak from end-stage 6MAT V̇O2: V̇O2peak (mL·kg−1·min−1) = 1.501(6MAT V̇O2) – 0.940. Correlation between measured and predicted V̇O2peak was excellent (r = 0.89). No significant difference was found between measured (17.41 ± 7.44 mL·kg−1·min−1) and predicted (17.42 ± 6.61 mL·kg−1·min−1) V̇O2peak (p = 0.97). When cross-validated with a sample of 10 individuals with SCI, correlation between measured and predicted V̇O2peak remained high (r = 0.89), with no differences between measured (18.81 ± 8.35 mL·kg−1·min−1) and predicted (18.73 ± 7.27 mL·kg−1·min−1) V̇O2peak (p = 0.75). Results suggest that 6MAT V̇O2 can be used to predict V̇O2peak among individuals with chronic SCI. The 6MAT should be used as a clinical tool for assessing aerobic capacity when peak exercise testing is not feasible.