Lineage tracing methods enable the identification of all progeny generated by a single cell. High-throughput lineage tracing in the mammalian brain involves parallel labeling of thousands of progenitor cells with genetic barcodes in vivo followed by single-cell RNA-seq of lineage relations and cell types. Here we describe the generation of barcoded lentivirus, microinjections into the embryonic day 9.5 mouse forebrain, dissociation of 2-week-old mouse brain tissue, single-cell RNA-seq library preparation, and data analysis using a custom software. Compared to traditional methods based on sparse fluorophore labeling of progenitor cells, lineage tracing with genetic barcodes and single-cell RNA-seq has a >100-fold higher throughput while using >10 times fewer mice.