Lateral Ankle Sprains (LAS) are among the 3 most common musculoskeletal conditions sustained by Canadian Armed Forces (CAF) members. Despite receiving comprehensive rehabilitation programs, military members with LAS have reported persistent symptoms, impairments and recurrences which impact their physical readiness, and consequently, the operational readiness of the military. These findings suggest that the use of comprehensive rehabilitation programs alone for treating LAS may not effectively address some of the impairments crucial for asymptomatic ankle function. Ankle dorsiflexion hypomobility is a common impairment in soldiers following LAS, which may cause functional difficulties and increase recurrence risk. Ankle mobilizations are commonly applied to restore dorsiflexion following LAS, but research into their clinical effectiveness is limited. This pilot study investigated the feasibility of conducting a randomized trial to determine the effectiveness of ankle mobilizations to improve dorsiflexion in CAF members with LAS. Twenty eligible subjects with acute LAS participated in a comprehensive rehabilitation program. Ten members were randomized to also receive ankle mobilizations, while the other ten received a sham. At baseline, 2 and 12 weeks measures of ankle dorsiflexion, pain, self-reported function, return to work and recurrences were recorded. Independent-T or Mann-Whitney U tests were used as appropriate to determine the mean differences between outcomes, Mixed Analysis Of Variance (MANOVA) for repeated measures was used to explore interactions between groups and time for ankle dorsiflexion, and correlational analyses were used to explore relationships between all outcomes. There were no significant differences in mean dorsiflexion between the mobilization (95.2 ± 47.5 mm) and sham groups (94.7 ± 36.9 mm) at 2 weeks (p = 0.84). There was a significant interaction between ankle dorsiflexion and time (p < 0.001), but not between groups (p = 0.460). There were no significant differences reported in pain or general self-reported function. However, clinically important changes in ankle dorsiflexion and general self-reported function were reported by both groups, and the magnitude of this change was larger in the mobilization group. These results reinforce the value of early and comprehensive rehabilitation for CAF members with LAS, and suggest that a full scale randomized trial is both feasible in a clinical CAF setting and warranted due to these preliminary findings.