The mechanisms involved in the processing of long non-coding RNAs (lncRNAs) are largely uncharacterized. Dhir et al. now find that transcription termination of lncRNA transcripts containing primary miRNAs (lnc-pri-miRNAs) — which encode 17.5% of human miRNAs — involves cleavage by the Microprocessor complex rather than the canonical cleavage and polyadenylation pathway. The Microprocessor complex, which comprises the double-stranded RNA-binding protein DGCR8 and the RNase III endonuclease Drosha, is known to process pri-miRNA-containing protein-coding transcripts to give rise to miRNAs. Here, the authors found that liver-specific lnc-pri-miR-122 is not polyadenylated but contains a cleavage site for Drosha at its 3′ end. Moreover, depletion of DGCR8 or Drosha led to readthrough transcription, indicative of a termination defect. Genome-wide chromatin RNA sequencing analyses in HeLa cells indicated that Microprocessor terminates transcription of most lnc-pri-miRNAs.