Purpose: To confirm whether peak aerobic capacity determined during laboratory testing could be replicated during an on-court field-based test in wheelchair rugby players. Methods: Sixteen wheelchair rugby players performed an incremental speed-based peak oxygen uptake ($\dot{\mathrm{V}}{\mathrm{O}}_2\text{peak}$) test on a motorized treadmill (TM) and completed a multistage fitness test (MFT) on a basketball court in a counterbalanced order, while spirometric data were recorded. A paired t test was performed to check for systematic error between tests. A Bland–Altman plot for $\dot{\mathrm{V}}{\mathrm{O}}_2\text{peak}$ illustrated the agreement between the TM and MFT results and how this related to the boundaries of practical equivalence. Results: No significant differences between mean $\dot{\mathrm{V}}{\mathrm{O}}_2\text{peak}$ were reported (TM: 1.85 [0.63] vs MFT: 1.81 [0.63] L·min⁻¹; P = .33). Bland–Altman plot for $\dot{\mathrm{V}}{\mathrm{O}}_2\text{peak}$ suggests that the mean values are in good agreement at the group level; that is, the exact 95% confidence limits for the ratio systematic error (0.95–1.02) are within the boundaries of practical equivalence (0.88–1.13) showing that the group average TM and MFT values are interchangeable. However, consideration of the data at the level of the individual athlete suggests that the TM and MFT results were not interchangeable because the 95% ratio limits of agreement either coincide with the boundaries of practical equivalence (upper limit) or fall outside (lower limit). Conclusions: Results suggest that the MFT provides a suitable test at a group level with this cohort of wheelchair rugby players for the assessment of $\dot{\mathrm{V}}{\mathrm{O}}_2\text{peak}$ (range 0.97–3.64 L·min^–1), yet caution is noted for interchangeable use of values between tests for individual players.