Purpose: This study aimed at investigating prognostic values of different ultrasound variables in predicting therapeutic outcome of the patients with carpal tunnel syndrome (CTS) after conservative treatment in a long-term follow-up data. Materials and Methods: One hundred and three participants with 162 affected hands were enrolled in this retrospective study. Records of baseline clinical information, nerve conduction studies (NCSs), and ultrasound assessment were retrieved. A structured telephone interview was conducted for acquiring patients’ response to recovery after treatment. Multinomial logistic regression analysis was used to estimate the odds ratio and 95% confidence interval of individual ultrasound variable, adjusted for age, gender, and other confounding factors. Results: Perimeter at wrist (W-P), ratio of cross-sectional area of wrist over one-third distal forearm (R-CSA), changes of CSA from wrist to the one-third distal forearm (△CSA), and changes of perimeter from wrist to one-third distal forearm (△P) were negatively and significantly associated with “improved” and “no change” categories relative to reference category (“deteriorated” category). After adjustment for age, gender, affected hand side, surgical history, and comorbidity, for one unit increase of W-P/△CSA/△P, the odds of “improved” category versus “deteriorated” category decreased by 89.1%/56%/95.2%, whereas the odds of “no change” relative to “deteriorated” category decreased by 77.8%/54.6%/84.9% should one unit increase in the correspondent individual ultrasound variable. Conclusion: Ultrasound variables can significantly predict therapeutic outcome in CTS after conservative management in a long-term follow-up. Further studies may be required to assess whether a combination of clinical, NCS, and ultrasound variables can better predict the therapeutic outcome.