A high proportion of children with speech impairments are found to be vulnerable to this disorder and it significantly impairs their social adjustment and skills. In light of this problem, this study investigated the effect of cognitive behavioural play therapy in decreasing social anxiety disorders in school children with speech impairments. This study is a group-randomized control group trial involving 122 schoolchildren in inclusive schools in Enugu state of Nigeria. We utilized Gpower statistical software to establish the adequacy of the sample size. Participants in the intervention group were exposed to a 12-week cognitive behavioural play therapy programme whereas those in the comparison group did not receive the therapy programme but were rather only assessed at three-time points using Severity Measure for Generalized Anxiety Disorder—Child Age 11–17 (SMGAD-C), and Liebowitz Social Anxiety Scale for Children and Adolescents, self-report version (LSAS-CA-SR). A multivariate analysis was used to analyze the data collected. The results showed that CBPT is significantly effective in lessening social anxiety disorders among children with speech impairments over time whereas no changes were observed among no-contact control group participants. Given the treatment outcome, this study finally suggests that CBPT intervention is effective and significant in decreasing social anxiety disorders in children with speech impairments.