Motivation undoubtedly plays an important role in learning a second language in that the whole process presupposes motivation to some extent. In the context of Syrian refugees, understanding the factors motivating learners is the very first step in the language learning process in that the refugees must first be integrated into the education system, which will soon facilitate adaptation to society. In this quantitative study, a cross-sectional survey model was employed to determine the reasons for Syrian adult refugees to learn Turkish and examine the influence of motivation on Turkish language achievement. The participants were Syrian adult refugees who learned Turkish as a second language in Turkey. The data of the study were obtained using a questionnaire including the "Motivation Scale for Learning Turkish as a Foreign Language" and the "Turkish Achievement Test" developed by the researchers. Data obtained from the motivation scale were analyzed quantitatively by using descriptive statistics, and the mean values and the standard deviations of the achievement test scores were calculated using SPSS. The results indicated that the main reasons Syrian refugees learn Turkish are professional career, academic career, survival needs and social adaptation. On the other hand, their motivations were found to be high, and it was revealed that refugees were mostly instrumentally motivated. While no significant differences were found in the level of motivation among of Syrian adult refugees in terms of their reasons for learning Turkish, the results clarified that motivation has a great role in raising proficiency in learning Turkish as a second language. Regarding the results of the study, it can be suggested that language teachers should be aware of various reasons of their learners to learn a language and seek ways to motivate them, which will support the learning process.