Abstract Background Hospitalisation-associated disability due to reduced physical activity levels and prolonged bedrest episodes are highly prevalent in older adults. Objective To assess the effect of gamified interventions on functional capacity in hospitalised older adults. Methods A three-armed non-randomised controlled trial with two experimental intervention groups and a control group was conducted in a tertiary public hospital in Navarre, Spain. Participants were allocated to a simple gamification group (SGG) (n = 21), a technology-based gamification group (TGG) (n = 23) or a control group (CG) (n = 26). The end points were changes in functional capacity, muscle strength, cognition, mood status and quality of life. Results Seventy patients (mean age 86.01 ± 4.27 years old) were included in the study; 29 (41.4%) were women. At discharge, compared to CG, a mean increase of 1.47 points (95%CI, 0.15–2.80 points) and 2.69 points (95%CI, 1.32–4.06 points) was observed (SGG and TGG, respectively) in the SPPB test; as well as an increase of 5.28 points (95%CI, 0.70–9.76 points) in the Barthel Index and 2.03 kg (95%CI, 0.33–3.72 kg) in handgrip strength in the TGG. Regression mediation analyses demonstrated that muscle strength changes (β = 1.30; 95%CI, 0.45–2.14; indirect effect 0.864; 95%CI, 0.09–1.90) significantly mediated the TGG effect on the SPPB score. Conclusions The TGG intervention programme may provide significant benefits in physical and muscle function over usual care and seems to reverse the functional decline frequently associated with acute hospitalisation in older adults.