Dental arch relationships (DARs) and palatal morphology (PM) were evaluated in in non-syndromic complete unilateral cleft lip and palate (UCLP) Italian patients after surgery. Pre- and postnatal factors affecting the results were investigated. Sixty-six children with UCLP (40 boys and 26 girls, with a mean age of 10.1 ± 2.9 years), predominantly Caucasian (77%), were consecutively enrolled in this cross-sectional study. Twenty children had received a one-stage protocol consisting of an early periosteal palate surgical repair and lip closure and forty-six were submitted to a staged surgical protocol with delayed palate repair (DPR). A single clinician collected data on their medical history and carried out a dental examination. The DAR and PM were graded on dental casts according to the Eurocran index and dichotomised as favourable and unfavourable based on the treatment outcome. Multiple logistic regression analyses demonstrated that female sex (OR = 6.08, 95% CI: 1.47–25.23, p = 0.013), DPR (OR = 4.77, 95% CI: 1.14–19.93, p = 0.032) and the use of a neonatal plate (OR = 4.68, 95% CI: 1.27–17.16, p = 0.020) increased the odds of having favourable DAR, while only DPR (OR = 9.76, 95% CI: 2.40–39.71, p = 0.001) was significantly associated with a favourable PM. Based on these findings, only DPR had a significantly favourable effect on both DAR and DM in Italian children with complete UCLP.