This systematic review focused on the common conventional physiotherapy interventions used with children with cerebral palsy (CP), aged 4 to 18 years, and critically appraised the recent evidence of each of these interventions using the Oxford Centre for Evidence-Based Medicine Levels of Evidence. The search strategy yielded 34 articles after inclusion and exclusion criteria were applied. The investigated physiotherapy interventions included strength and functional training, weight-supported treadmill training (WBSTT), and neurodevelopmental treatment (NDT). A category of treatment dosage was also included. Strength training was the most studied intervention with significant improvements found in the strength of selected muscle groups using dynamometry, with fewer studies showing significant improvement in function. Functional training showed improvements in gross motor function, endurance, and temperospatial measures, such as gait speed and stride length. Nonsignificant trends of improvement on the Gross Motor Function Measure (GMFM) and gait velocity were found for WBSTT by a few studies with low levels of evidence (case series). Of three studies that evaluated NDT, one high-level evidence study, i.e., randomized controlled trial (RCT) found significant improvements on the GMFM. All studies reviewing treatment dosage had high levels of evidence (RCTs), yet found no significant differences for different intensities of treatment. These results indicate that the levels of evidence for physiotherapy interventions, particularly strengthening and to a lesser extent functional training, in school-aged children with CP has improved; however, further high-level evidence is needed for other interventions.