The aim of this study was to evaluate the effect of an eight-week whole body vibration (WBV) on lower extremity spasticity and ambulatory function in children with cerebral palsy with a complete crossover design. Sixteen participants aged 9.2 (2.1) years participated in this study. Half of the participants received a 10-min WBV, 3 times a week for 8 weeks. Then a 4-week washout period followed, after which they received a sham WBV 3 times a week for 8 weeks. The other half received the intervention in a reversed order. The participants were evaluated via variables measuring range-of-motion, muscle tone, and ambulatory function before, immediately after, 1 day after, and 3 days after each intervention. Repeated-measures analyses revealed significant beneficial effects on most variables expect the passive range-of-motion measurement. Significant correlations were found between timed up-and-go and relaxation index, and between timed up-and-go and six-minute walk test. The results suggested that an 8-week WBV intervention normalized muscle tone, improved active joint range and enhanced ambulatory performance in children with cerebral palsy for at least 3 days. These indicated that regular WBV can serve as an alternative, safe, and efficient treatment for these children in both clinical and home settings.