Background: The interest in ultrasonography (US) and magnetic resonance imaging (MRI) assessment of the patients with carpal tunnel syndrome (CTS) is growing. This paper aimed to find the correlation of postoperative changes in these modalities’ parameters with clinical outcomes. Methods: Boston CTS questionnaire-symptom severity (BQ-SS), Boston CTS questionnaire-functional status (BQ-FS), and visual analog scale (VAS) questionnaires (for pain, paresthesia, and grip weakness assessment) were used to evaluate clinical outcomes. Various imaging parameters of the median nerve and carpal tunnel were evaluated using US and MRI at two levels of the hook of the hamate (distal) and the pisiform (proximal) once preoperatively and then 3 months postoperatively. Corresponding US and MRI parameter measures were compared, and correlational analysis was performed between alteration of imaging findings and changes in clinical parameters postoperatively. Results: Patients’ functional status (BQ-FS score) was positively correlated with the nerve width both in US and MRI at the proximal level (r = 0.457 and r = 0.453, respectively) and also with the MRI nerve circumference at the distal level (r = –0.482). Correlation between paresthesia and the nerve width was notable in MRI at the distal hook of the hamate level (r = –0.403). Grip weakness VAS score was correlated with the nerve width-to-height ratio (WHR) in US at the distal level (r = 0.432). Conclusions Changes in US and MRI parameters of the median nerve width, circumference, and WHR were associated with clinical changes in patients with CTS after surgery.