Purpose: To evaluate the impact of a myopia control (MC) spectacle lens incorporating peripheral defocus on functional visual parameters compared to conventional single vision (SV) lenses. Methods: Thirty-nine young adults (age 21.1 ± 1.3 years; spherical equivalent −2.85 ± 2.8 D) participated in this single-session, within-subject crossover design. Distance and near LogMAR VA were assessed centrally and at 22° nasal and temporal off-axis. Distance contrast sensitivity (CS) was measured across five spatial frequencies (1.5–18 cpd) and the Area Under the Log CS Function (AULCSF) calculated. Retinal sensitivity was evaluated using automated static perimetry. Dynamic visual performance was assessed using a standardized video game platform. Outcomes were compared using repeated measures ANOVA or Wilcoxon signed-rank tests. Results: Central VA was comparable between lens types. MC lenses significantly reduced off-axis distance VA (nasal: 0.35 ± 0.15 LogMAR; temporal: 0.20 ± 0.14 LogMAR; both p < 0.001) and near VA (nasal: 0.72 ± 0.25 LogMAR; temporal: 0.34 ± 0.2 LogMAR; both p < 0.001). Off-axis AULCSF was significantly reduced with MC lenses (nasal: 12.07 ± 5.06 vs. 26.37 ± 5.00 units; temporal: 13.00 ± 6.93 vs. 27.14 ± 4.64 units; both p < 0.001), while central AULCSF remained similar between lens types (SV: 27.87 ± 5.04 vs. MC: 27.15 ± 5.02 units; p = 0.277). No significant differences were found for visual field indices (all p > 0.05). Video game accuracy was comparable between lenses, but task completion time was slower with MC lenses (20.71 ± 10.08 vs. 18.39 ± 6.65 s; p = 0.012). Conclusions: MC spectacle lenses preserve central VA, CS, and visual field sensitivity but induce significant off-axis VA and off-axis CS reductions. Dynamic visuomotor accuracy is maintained, though task completion speed is modestly reduced. These functional trade-offs should be considered when prescribing MC lenses.