Task motivation has recently gained prominence in second language (L2) research. However, its potential effects on the transfer of learning across tasks have not been investigated. The present study sought to deal with this issue through a mixed-methods approach. A total of 82 intermediate English learners took part in the study. Initially, they were tested regarding their knowledge of the English definite article. Then, they performed a consciousness-raising task that accentuated the article. Following the task, their task motivation was measured using a self-report questionnaire. After a few days, they completed another task requiring the knowledge of the article to see whether those who experienced higher task motivation on Task 1 were able to transfer the newly gained knowledge more efficiently to Task 2 compared to learners with low task motivation. Then, focus group interviews were conducted with learners representing both groups. Analysis of variance revealed that task motivation significantly affects transfer of learning. Moreover, thematic coding analysis of the qualitative data indicated that positive task appraisal, peer effect, increased effort, and activating self-regulation strategies were the major factors associated with high task motivation leading to efficient transfer of learning. The findings suggest some implications for pedagogy and research.