Background: Paternalism/overprotection limits communication between healthcare professionals and patients and does not promote shared therapeutic decision-making. In the global north, communication patterns have been regulated to promote autonomy, whereas in the global south, they reflect the physician’s personal choices. The goal of this study was to contribute to knowledge on the communication patterns used in clinical practice in Mexico and to identify the determinants that favour a doctor–patient relationship characterized by low paternalism/autonomy. Methods: A self-report study on communication patterns in a sample of 761 mental healthcare professionals in Central and Western Mexico was conducted. Multiple ordinal logistic regression models were used to analyse paternalism and associated factors. Results: A high prevalence (68.7% [95% CI 60.0–70.5]) of paternalism was observed among mental health professionals in Mexico. The main determinants of low paternalism/autonomy were medical specialty (OR 1.67 [95% CI 1.16–2.40]) and gender, with female physicians being more likely to explicitly share diagnoses and therapeutic strategies with patients and their families (OR 1.57 [95% CI 1.11–2.22]). A pattern of highly explicit communication was strongly associated with low paternalism/autonomy (OR 12.13 [95% CI 7.71–19.05]). Finally, a modifying effect of age strata on the association between communication pattern or specialty and low paternalism/autonomy was observed. Conclusions: Among mental health professionals in Mexico, high paternalism prevailed. Gender, specialty, and a pattern of open communication were closely associated with low paternalism/autonomy. Strengthening health professionals’ competencies and promoting explicit communication could contribute to the transition towards more autonomist communication in clinical practice in Mexico. The ethical implications will need to be resolved in the near future.