Background The postoperative speech outcomes of submucous cleft palate (SMCP) surgery are known to be poorer than those of other types of cleft palate. We attempted to objectively characterize the postoperative complications and speech outcomes of the surgical treatment of SMCP through a comparison with the outcomes of incomplete cleft palate (ICP). Methods This study included 53 SMCP patients and 285 ICP patients who underwent surgical repair from 1998 to 2015. The average age of the patients at the time of surgery was 3.9±1.9 years for the SMCP patients and 1.3±0.9 years for the ICP patients. A retrospective analysis was performed of the complications, the frequency of subsequent surgical correction for velopharyngeal dysfunction (VPD), and speech outcomes. Results In both the SMCP and ICP patients, no cases of respiratory difficulty, bleeding, or wound disruption were noted. Delayed wound healing and fistula occurred in 18.9% and 5.7% of the SMCP patients and in 14% and 3.2% of the ICP patients, respectively. However, no statistically significant difference in either delayed wound healing or fistula occurrence was observed between the two groups. The rate of surgical correction for VPD in the SMCP group was higher than in the ICP group. In the subset of 26 SMCP patients and 62 ICP patients who underwent speech evaluation, the median speech score value was 58.8 in the SMCP group and 66 in the ICP group, which was a statistically significant difference. Conclusions SMCP and ICP were found to have similar complication rates, but SMCP had significantly worse speech outcomes.