RNA modifications constitute an essential layer of gene regulation in living organisms. As the most prevalent internal modification on eukaryotic mRNAs, N6-methyladenosine (m6A) exists in many plant species and requires the evolutionarily conserved methyltransferases, demethylases, and m6A binding proteins for writing, erasing, and reading m6A, respectively. In plants, m6A affects many aspects of mRNA metabolism, including alternative polyadenylation, secondary structure, translation, and decay, which underlies various plant developmental processes and stress responses. Here, we discuss the recent progress in understanding the roles of m6A modification in mRNA metabolism and their mechanistic link with plant development and stress responses. We also highlight some outstanding questions and provide an outlook on future prospects of m6A research in plants.