Previous studies have examined the effectiveness of joint mobilisations, more specifically, Mobilisation with Movement (MWM) to increase weight bearing (WB) dorsiflexion (DF) Range of Movement (ROM) and dynamic balance in individuals with chronic ankle instability (CAI). While MWMs have increased DF ROM in individuals immediately, examining the effects of MWM over a period of a week on DF ROM and dynamic balance would provide more evidence for a long-term effect. This study aimed to determine if MWMs would improve DF ROM and Y-balance test (YBT) reach distances in those with CAI lasting one week. Twelve participants with CAI (12 males, age: 21.50 ± 1.09 years; height: 178.83 ± 4.51 cm; mass: 88.70 ± 15.59 kg, Foot and Ankle Disability Index: 75.5 ± 8.33) volunteered in this repeated-measures study. Participants received two interventions; five-minute rest (control) and one MWM treatment with each on separate weeks. WB DF ROM (cm) and normalised YBT reach distances (%) were assessed prior the intervention (pre), immediately after the intervention (post), 24 hours following the intervention, 48 hours following the intervention, and finally one week following the intervention. Significant increases were found in DF ROM in; pre and post intervention; pre and 24 hours and pre and 48 hours follow up, (p < 0.001) however not significant pre and one week follow up (p > 0.05). There were also significant increases in the posterolateral reach distance in pre and 24 hours and pre and 48 hours follow up (p <0.0125) and in the posteromedial reach distances in all the time measurements, (p <0.0125). There were no significant increases in the anterior reach in any of the time measurements (p > 0.05). These results indicate the MWM intervention did not improve the anterior reach distance of YBT. However, MWM did improve DF ROM and the posterolateral and posteromedial reach distances of YBT for at least 48 hours. Further research should investigate the treatment parameters of MWMs, how to prolong the effects of MWM and the arthrokinematics deficiencies found in those with CAI.