Discourse markers (DMs) instruction is currently receiving an increasing amount of attention in the literature on second language learning. As noted by Al-Yaari, Al Hammadi, Alyami, and Almaflehi (2013), and Algouzi (2014), the use of DMs is insufficient to support the development of the language skills, especially reading, of Saudi English as a Foreign Language (EFL) learners’. Recurrent reports (e.g., Al Abik, 2014; Al-Mansour & Al-Shorman, 2011) have shown that Saudi EFL learners perform poorly on reading comprehension tasks. Since these studies were generally descriptive, the current study attempted to fill the gap by providing empirical data, particular to low-proficiency learners in the Saudi EFL context, based on an eight-session intervention programme to familiarise learners with DMs. This study hypothesised that explicit DM instruction could improve learners’ reading comprehension and that there would be a significant positive relationship between Saudi EFL learners’ knowledge of DMs and their reading performance. To test these hypotheses, two classes with a total of 70 Saudi male third-grade secondary students were assigned as control and experimental groups. The experimental group was introduced to the intervention programme, whereas the control group was only taught the prescribed reading lessons. Two forms of tests in both DMs and reading comprehension were administered to the two groups before and after the intervention. A correlation analysis was also run to determine the relationship between learners’ knowledge of DMs and their reading performance. Results confirmed, with a large effect size, that explicit instruction in DMs improved low-proficiency EFL learners’ reading comprehension. The finding also suggested that knowledge of DMs correlated highly with reading comprehension. In other words, learners who were good at recognising DMs performed better in reading comprehension tasks, whereas those who were poor at recognising DMs performed poorly. Practical suggestions for pedagogy and future research were also identified.