The mechanistic understanding of nascent RNAs in transcriptional control remains limited. Here, by a high sensitivity method methylation-inscribed nascent transcripts sequencing (MINT-seq), we characterized the landscapes of N6-methyladenosine (m6A) on nascent RNAs. We uncover heavy but selective m6A deposition on nascent RNAs produced by transcription regulatory elements, including promoter upstream antisense RNAs and enhancer RNAs (eRNAs), which positively correlates with their length, inclusion of m6A motif, and RNA abundances. m6A-eRNAs mark highly active enhancers, where they recruit nuclear m6A reader YTHDC1 to phase separate into liquid-like condensates, in a manner dependent on its C terminus intrinsically disordered region and arginine residues. The m6A-eRNA/YTHDC1 condensate co-mixes with and facilitates the formation of BRD4 coactivator condensate. Consequently, YTHDC1 depletion diminished BRD4 condensate and its recruitment to enhancers, resulting in inhibited enhancer and gene activation. We propose that chemical modifications of eRNAs together with reader proteins play broad roles in enhancer activation and gene transcriptional control. Display omitted •MINT-seq is of high sensitivity to characterize m6A methylome on nascent RNAs•There is a pervasive but also selective m6A deposition to long and stable eRNAs•m6A-eRNAs recruit YTHDC1 to enhancers to stimulate enhancer and gene activation•m6A-eRNA/YTHDC1 phase separate to facilitate transcriptional condensate formation Lee, Wang, Xiong, et al. characterized nascent RNA m6A methylome in human cells, finding a pervasive existence of m6A-marked eRNAs. These m6A-modified eRNAs recruit the nuclear m6A reader YTHDC1 to partition into liquid-like condensates, which facilitate formation of transcriptional activator condensates and therefore gene activation.