The present study investigated how Cantonese speakers learning English as a second language (L2) would comprehend English irony and whether their L2 proficiency and use would moderate their irony processing. Thirty Cantonese speakers with differing English proficiency (intermediate vs advanced) were asked to complete an irony comprehension task in which they had to determine if given comments in literal or ironic situations were positive or negative. The irony comprehension task was immediately followed by a stimulated recall session to further explore the participants' thought processes while responding to the irony comprehension items. The results revealed that the participants were faster and more accurate when processing positively-valenced comments (literal praise, ironic criticism), compared to negatively-­valenced ones (literal criticism, ironic praise). The findings suggest that learners had greater difficulty identifying ironic praises than ironic criticisms, underscoring the role of valence in second language irony inferencing. The stimulated recall data suggested that the anticipation of irony may accelerate the identification of ironic criticisms. While proficiency facilitated the speed of irony comprehension, the duration of L2 use, especially in speaking, emerged as an important factor in moderating the accuracy of irony comprehension.