Walking is an effective, well accepted, inexpensive, and functional intervention. This study compared the outcomes and changes in walking behavior of self-monitored (SM) and supervised (SU) walking interventions for older adults.Participants were assigned to SM (n = 21) and SU (n = 21) walking groups according to their place of residence. Both groups exercised and wore a pedometer for 3 months.The outcome measures were step count, body mass index (BMI), and physical function. Two-way repeated-measure ANOVA and independent t tests were used to compare the intervention effects. We also plotted the trends and analyzed the walking steps weekly.Only BMI exhibited a group × time interaction. The pre-posttest differences showed knee extension muscle strength (KEMS) and Timed Up and Go test were significantly improved in the SM group, whereas BMI, KEMS, 30-s sit-to-stand, functional reach were significantly improved, but 5-m gait speed significantly slower in the SU group. For participants attending ≥50% of the sessions, those in the SM and SU groups had similar results for all variables, except for 2-min step (2MS) and daily walking step counts.Both self-monitored and supervised walking benefit older adults in most physical functions, especially lower-extremity performance, such as muscle strength, balance, and mobility. The effects of both programs do not differ significantly, except for BMI and 2MS (ie cardiopulmonary endurance). We recommend pedometer-assisted self-monitored walking for older adults because of its ability to cultivate exercise habits over the long term, whereas supervised walking to establish effective exercise intensity.