Background Skin signs observed in morbid obesity may change as the weight reduces, especially post-bariatric surgery (BaS). Data concerning the skin findings exclusively in post-BaS patients remain limited. Methods Seventy post-BaS patients were examined for cutaneous abnormalities. The patients were divided into those with successful weight loss (% excessive body weight loss (EBWL) of at least 50%) and a non-successful group (%EBWL < 50%). Results Forty-six patients with successful weight loss demonstrated a significantly lower prevalence of acanthosis nigricans on the neck, axillae and inguinal areas, keratosis pilaris (KP) and pebble fingers. However, a higher prevalence of alopecia was observed. After adjustment with patients’ factors, KP (adjusted odds ratio (aOR) = 0.21, 95%CI 0.06–0.74, p = 0.02) and pebble fingers (aOR = 0.09, 95%CI 0.01–0.89, p = 0.04) remained significantly less likely in patients with successful weight loss. Laboratory results comparing pre- and post-surgery values revealed significant decreases in fasting plasma glucose, hemoglobin A1c, and triglyceride and an increase of high-density lipoproteins in both groups. However, significant decreases of liver aminotransferases (AST and ALT) were observed only in the successful group (p = 0.04, 0.003). Nonetheless, a decrease in vitamin B12 (p = 0.01) was observed in the successful group. Conclusion Weight loss after BaS provided an improvement for metabolic profiles. Successful weight reduction resulted in better skin improvement. However, nutritional supplements may be necessary. Trial registration Thai Clinical Trials Registry TCTR20171003002. Registered October 3. 2017, retrospectively registered.