Stroke-related upper limb dysfunction and spasticity are main causes of long-term disability which affect functional independence and quality of life notably among patients. Segmental muscle vibration (SMV) has arisen as a promising rehabilitation approach to improve motor recovery and reducing spasticity in poststroke patients. This study aimed to compare the effects of the SMV on upper limb function and spasticity in subacute poststroke patients treated with two vibration frequencies (i.e., 60 Hz and 120 Hz) with those of patients treated with traditional therapy alone. Twenty-eight participants (N = 28) were randomized into three groups including two experimental groups that received extra SMV at 60 Hz and 120 Hz, and a control group that received conventional physiotherapy. The interventions were provided twice a week for eight weeks. The study employed Fugl-Meyer Assessment for Upper Extremes (FMA-UE), Modified Ashworth Scale (MAS) and Motor Assessment Scale were used to measure the outcomes. Upper limb function showed significant improvements across all groups and a decrease in spasticity at baseline (p < 0.05). Nevertheless, the postintervention between-group results were not significantly different between two SMV and control groups (p > 0.05). SMV in combination with traditional therapy is effective, but there was no difference in the benefits of 60 Hz versus 120 Hz in patients with subacute stroke treated with conventional therapy alone.