The aim of this study was to detect effects of ultrasound-guided botulinum toxin type-A (US-guided BoNT-A) injections prepared according to lower extremity innervation zones on spasticity and motor function in 3-16 years children with diplegic and hemiplegic spastic cerebral palsy. This study included 25 patients between 3 and 16 years of age who admitted to our clinic in 2017, were being followed in our clinic with a diagnosis of cerebral palsy, had BoNT-A injections due to lower extremity spasticity. The US-guided BoNT-A injections were administered into the spastic muscles using a specific approach according to innervation zones of muscle. Modified Ashworth Scale (MAS) and Gross Motor Functional Classification System (GMFCS) were assessed at the baseline, and 4 and 12 weeks after the BoNT-A injections. Minimum and maximum ages of the patients were 45 and 192 months, and gender distribution was 8 females and 17 males. Significant decreases in the MAS scores of the knee and ankle tones were measured 4 and 12 weeks after the BoNT-A injection when compared to the baseline scores (p < 0.025). Hip muscle tonus only decreased 12 weeks after the injection (p < 0.025). In parallel with a reduction in spasticity GMFCS improved from 3 to 2 in the 4th and 12th weeks. US-guided BoNT-A injections with Euro-musculus approach is a practical and effective method to perform injections into proper points of proper muscles in children with spastic cerebral palsy.