Islam has five pillars and specific practices that foster subjective well-being (SWB). There exists empirical evidence supporting religiosity and SWB association in different Muslim countries – mainly Arabic. Significant associations were found between religiosity and SWB, happiness, optimism, satisfaction with life, love of life, mental health, physical health (positive), as well as ill-being, such as anxiety, depression, neuroticism, and PTSD (negative). Reviewed research examined the effect among Arab Muslims as well as non-Arab Muslims living as a religious or ethnic minority in majority Christian nations. The reviewed studies included participants in different age groups from 14 to 60 years old. The present results are consistent with previous studies carried out in different countries, situations, cultures, and religions. It seems true that the religion of Islam as a value system has a high rank and importance among its believers. It was concluded that psychotherapists should attend to client's religiosity in clinical settings.