The COVID-19 pandemic has compelled global higher education institutions, e.g. in Laos, to suddenly switch to online learning platforms without planning for multidimensional challenges to overcome. This study aimed to investigate Lao EFL undergraduate students' motivation and challenges for learning English during and post COVID-19. The participants comprised 75 students studying in various food science programs at a Lao university. This research adopted a mixed-methods design that integrated quantitative and qualitative approaches. The research tools consisted of questionnaires and semi-structured interviews. The results showed a moderate level of integrative motivation among students during the pandemic, which subsequently escalated to a high level after the COVID-19 pandemic. Meanwhile, their instrumental motivation remained consistently high throughout both pandemic periods. The findings also revealed a slight decrease in student challenges during the pandemic, transitioning from high to moderate levels compared to the post-pandemic period. Students encountered difficulties in developing self-regulation skills during and after the COVID-19 pandemic, along with added financial burdens, including increased living costs in the post-pandemic period. Face-to-face learning was preferred by students. Moreover, these findings provided valuable insights, pedagogical implications, and recommendations to address emerging technological trends in English language education.