There is emerging evidence that suggests emotions as a discrete factor in academic online contexts that significantly contribute to student engagement and higher order learning (Cleveland-Innes & Campbell, 2012; You, 2012, You & Kang, 2014; Zembylas, 2008; Liaw, 2008). Pekrun (2000) and Pekrun, Goetz, Frenzel, Barchfeld, and Perry (2011) developed the control-value theory of achievement emotion that not only showed that emotions represent a discrete category in student engagement, but that there are certain factors such as perceived academic control and self-regulation that function as antecedents of students' emotional reactions that affect online learning. The aim of the present paper is to review the emerging research evidence of the impact of emotions on students' engagement in order to understand the distinct role that emotions may play in online learning. The review also proposes strategies and activities that teachers can use in order to enhance students' positive engagement in online learning. The findings suggest that emotions are significant factors in students' engagement in online learning while cognitive and behavioural factors function as antecedents of emotions in online contexts. The inclusion of emotional, cognitive and behavioural strategies in online teaching can enhance students' engagement and learning experience in the online classroom.