This study explores how reading comprehension competencies influence linguistic achievement among learners of Arabic as a second language. Through a descriptive and semi-experimental approach, the research analyzes the connection between different levels of comprehension—literal, analytical, interpretive, and evaluative—and various aspects of language performance, including vocabulary knowledge, grammatical structures, morphology, writing, and spelling. The study sample consists of 96 learners enrolled in Level 3 of the Al-Misbah Program, and data were gathered using two validated instruments to ensure reliable measurement. The findings demonstrate that reading comprehension has a significant impact on overall linguistic achievement, though the degree of influence varies across language components. The strongest effects appear in vocabulary, structures, and writing skills, while morphology shows moderate to strong improvement. Higher-order comprehension skills, particularly interpretation, evaluation, and creative engagement with texts, contribute substantially to students’ ability to process, analyze, and use language effectively. The study concludes that reading comprehension competencies form a foundational element in the development of linguistic proficiency. It recommends incorporating structured comprehension strategies into Arabic language curricula and designing assessment tools that reflect the interconnected nature of language skills, thereby supporting a more holistic learning experience.