This study compared the modification of musculoarticular stiffness (MAS) and clinical outcomes after mobilization with movement (MWM) on the inferior tibiofibular joint and a placebo MWM. Moreover, injured and non-injured ankle MAS were compared after MWM therapy. A single-blinded randomized trial was conducted on 75 participants (mean age: 22.3 ± 2.17 years) with chronic self-reported asymmetric perception of ankle dorsiflexion stiffness. Participants were allocated to one of three groups: inferior tibiofibular MWM (ITFMWM), placebo and non-injured. Sinusoidal oscillation methods were used for experimental quantification of the MAS and clinical outcomes were assessed using the weight-bearing lunge test (WBLT), pain and stiffness perception. Three assessments were made: one pre-treatment (T0), one after the manual technique (T1) and one after taping (T2). Two-way ANOVA showed no significant differences between the groups and no interaction effect for the outcome measures. However, a significant difference for the time effect (T0-T1-T2) was found in the three groups for WBLT dorsiflexion range of motion (p < 0.001, Cohen's d = 0.21) and stiffness perception (p < 0.001, Cohen's d = 0.54) but the minimal clinically important differences were not reached for either value. The results could not support that a single session of ITFMWM modifies MAS or the clinical outcomes compared to placebo treatment. Furthermore, injured MAS does not differ from non-injured MAS in chronic ankle dorsiflexion stiffness. Further studies should assess subjects' responsiveness concerning the Mulligan concept and focus on a medium- to long-term follow-up.