The paper is about the effectiveness of using WhatsApp in teaching and learning Bahasa Malaysia as a foreign language to international students at the Universiti Sains Malaysia (USM) Engineering Campus especially during pandemic Covid-19 issues. An experimental teaching approach is adopted in teaching language at USM Engineering Campus, involving Bahasa Malaysia language course. The research is on how students are able to learn more effectively by using WhatsApp in online learning, in order to develop their language proficiency in Bahasa Malaysia as a foreign language will be described. Experience from the experimental teaching and learning approach through “FUN WITH LANGUAGE IN ONLINE CLASS- through WhatsApp” provides valuable information on how students react towards WhatsApp application and how do they acquire their language skills through language learning activities.