This study compared the effects of a 4-week supervised (SUP) and unsupervised (UNSUP) resistance training programme followed by 12 weeks of detraining (DET). Thirty-six healthy aging adults (age: 53.6 ± 3.6 years; body mass index: 28.3 ± 5.1 kg/m2) were randomly allocated to a SUP group (n = 17) or an UNSUP group (n = 19). Participants completed three training sessions per week using resistance bands and body weight movements. Measures of physical performance were administered at baseline, at the end of the training programme, and after the DET period. Function was assessed with the six minute walk test (6MWT), timed up-and-go (TUG), 30 s chair sit-to-stand (STS), stair-climb test (SCT), 40 m fast-paced walk test (FPWT) and sit-and-reach test (SRT), whereas the isometric mid-thigh pull (IMTP) and hand grip test were used to measure muscle strength. Following training, improvements in performance were found in the 6MWT, TUG, 30 s chair STS, SCT, FPWT, SRT, and IMTP (p < 0.05), with no significant differences between groups (p > 0.05). In addition, the majority of training-induced improvements remained significantly above baseline values after the DET period (p < 0.05). No significant between-group differences were observed following training or DET (p > 0.05). Four weeks of either SUP or UNSUP resistance training is sufficient to substantially improve muscle strength and function in aging adults, and these gains are largely preserved following prescribed exercise cessation. Home-based resistance training appears to be a practical and effective alternative to traditional SUP programmes that may help circumvent many barriers to physical activity in aging adults.