Vocabulary has been recognized as crucial for students who learn Arabic as a foreign language. Students need more Arabic vocabulary to acquire Arabic language skills. This present study was concerned with developing and assessing the content validity of an Arabic vocabulary achievement instrument for digital storytelling-based application. The instrument developed consisted of 40 items. 12 experts in the Arabic field determined the content validity scale of the instrument. This instrument was then administered to 40 Malaysian secondary school students. The result showed high content validity and reliability with all items displaying a positive value. The analysis used Cronbach's alpha to test the internal consistency reliability, and the alpha value showed .810 indicated very reliability. Therefore, present findings suggest that the instrument's content validity and composite reliability are appropriate for evaluating students' enhancement toward learning Arabic vocabulary.