Background: Health professionals present a greater vulnerability to the effects of COVID-19 on their mental health, especially those who work with vulnerable groups such as those who suffer from intellectual disability (ID). The objective of the present research was to develop and verify the effectiveness of a psychological intervention for professionals in the field of ID to improve their mental health during this health crisis. Methods: A total of 32 professionals participated. The variables measured were: post-traumatic growth, mental health, burnout, coping strategies, resilience, life satisfaction, optimism, and cognitive and affective empathy. Results: The results revealed statistically significant differences in the post-traumatic growth variable. In the rest of the variables (mental health, burnout, coping strategies, resilience, vital satisfaction, optimism, and empathy), no significant differences between groups were found. Conclusions: An increase in the levels of post-traumatic growth was observed in the intervention group after a brief online psychological intervention. However, given the small sample size, these results should be taken with caution. Institutions should foster and promote interventions aimed at reducing the high emotional impact produced by COVID-19 in professionals that care for people diagnosed with ID