The present study aimed to investigate the possible relationship between ESP learners’ critical thinking abilities and their reading comprehension. For this purpose, from the population of students studying in different fields of engineering at Amol Islamic Azad University, a sample of 202 ESP participants were selected based on a purposive sampling method. A critical thinking questionnaire was then given whereby the targeted respondents answered the prompts underlying the critical thinking construct. Subsequently, a valid reading comprehension test with an acceptable reliability index was administered and the data were analyzed using the related descriptive and inferential statistics. The findings revealed that there was a robust and positive correlation between ESP learners’ levels of critical thinking ability and their reading comprehension. Moreover, it was found that ESP students regarded as high critical thinkers significantly outperformed those with lower levels of critical thinking on the reading comprehension test. Notably, the results may offer useful implications to both language teachers and English learners indicating that critical thinking strategies play a pivotal role in the reading comprehension process.