This study describes adult learners' understanding in learning Islam using andragogy approach in which the study was conducted in Kampung Siglap Mosque and Al-Zuhri Higher Learning Institute. Prophet Muhammad (peace be upon him) educate his companions of who are adults from the shackles of "jahiliyyah," spiritual and intellectual darkness which includes the culture of silence and structural poverty towards Islam. Islam as taught by Prophet Muhammad since he first received the revelation has been through 14 centuries. Learn Islam remains the duty of Muslims. Many Islamic education models focused on the education of children but not for adult learners. Muslim adult learners have become the subject of experimentation using the trial and error method in deciding ideal education model. Singapore is a secular state where freedom of religion is encrypted in the constitution and Malay/Muslim comprises 13.3% of the population. Adults learn Islam to deepen their understanding and to practice the teachings of Islam due to their strong conviction to the religion. To illustrate this study, a qualitative research was adopted. The source of the research data come from the Muslim adult learners who attended the Islamic religious class either at Kampung Siglap Mosque and/or Al-Zuhri Higher Learning Institute. To determine the source of the data, the snowball sampling was used. The emphasis of this study are on adult learners understanding in learning Islam, adult learners approach to learning Islam and adult learners' transformation from the learning of Islam. The findings of this research illustrate adult learners' positive attitude in learning Islam, the intent of transforming to be an excellence Muslims, different styles of understanding Islam, characteristics of the learners who wanted to practice Islam. Adult learners formulated their own comprehension through their personal experiences. Adult learners initiated their own learning, inquisitive and engaged. They have a preconceived idea of learning the topics based on their needs related to Islam. Adult learners' eagerness to learn depended on teachers teaching method. They aspired to be responsible Muslim and role model to family members inspired them to achieve their learning goals; having self-confidence and family support facilitates their learning of Islam effectively. The intention establishes on adult learners strengthen their determination to actualize the intention of learning Islam is to succeed in life and the hereafter. In conclusion, what is understood by adult learners as correct is not necessarily true and what is understood by adult learners as incorrect is not necessarily wrong so adult learners understanding of Islam are shape by divine intervention. Adult learners learning experience has the elements of spirituality that provide them with a different level of enlightenment that includes understanding, insightful, self-reflection, critical and analytical, self-awareness, knowledge-oriented, wisdom, spiritual advancement, aroused morale, character refinement, and cultivation of curiosity. This understanding in learning Islam is different from the assumption of learning non-religious, which states that learning is equipping with particular competencies; learning is imparting of information and technology; and learning is for passing of examination. The outcome of the learning process in learning Islam involves physical and spiritual transformation of adult learners' personality.