The sensitivity of chromatin immunoprecipitation (ChIP) assays poses a major obstacle for epigenomic studies of low-abundance cells. Here we present a microfluidics-based ChIP-seq protocol using as few as 100 cells via drastically improved collection of high-quality ChIP-enriched DNA. Using this technology, we uncovered many new enhancers and super enhancers in hematopoietic stem and progenitor cells from mouse fetal liver, suggesting that enhancer activity is highly dynamic during early hematopoiesis.