The objective of this study was to investigate the feasibility of ballistic strength training (BST) to improve the mobility of individuals recovering from traumatic brain injury (TBI) in an inpatient rehabilitation centre. Participants had a maximum of eight usual physiotherapy sessions substituted with BST sessions. The feasibility of BST was assessed in terms of recruitment, attendance, adverse events (AEs), and participant acceptability of the intervention. The clinical aspects of feasibility were assessed by recording the ability of participants to complete the exercises and acquire skills. Secondary measures included the 10-metre walk test, the 6-minute walk test, and the Global Rating of Change scale. Fourteen of 22 eligible individuals with TBI in an inpatient rehabilitation centre consented to participate in the study, of whom two were excluded. No intervention-related AEs occurred. Participants attended 97% (71/73) of the total sessions. Participants positively accepted the intervention as rated on a visual analogue scale, M (SD) = 9.2 (0.9). All participants were able to complete the BST exercises. Participants significantly improved comfortable walking speed and walking capacity (p < 0.01). Participants perceived a meaningful change in walking ability. BST appears to be a promising rehabilitation method that may improve the walking outcomes of individuals with TBI in an inpatient rehabilitation setting. Larger-scale clinical trials are warranted.