p57Kip2 is a cyclin/CDK inhibitor and a negative regulator of cell proliferation. Here, we report that p57 regulates intestinal stem cell (ISC) fate and proliferation in a CDK-independent manner during intestinal development. In the absence of p57, intestinal crypts exhibit an increased proliferation and an amplification of transit-amplifying cells and of Hopx+ ISCs, which are no longer quiescent, while Lgr5+ ISCs are unaffected. RNA sequencing (RNA-seq) analyses of Hopx+ ISCs show major gene expression changes in the absence of p57. We found that p57 binds to and inhibits the activity of Ascl2, a transcription factor critical for ISC specification and maintenance, by participating in the recruitment of a corepressor complex to Ascl2 target gene promoters. Thus, our data suggest that, during intestinal development, p57 plays a key role in maintaining Hopx+ ISC quiescence and repressing the ISC phenotype outside of the crypt bottom by inhibiting the transcription factor Ascl2 in a CDK-independent manner. Display omitted •p57kip2 regulates intestinal stem cell proliferation in a CDK-independent manner•p57Kip2 is expressed in Hopx+ cells during embryonic development•p57Kip2 represses the transcriptional activity of Ascl2•p57Kip2 participates in the recruitment of a transcriptional corepressor complex During intestinal development, p57Kip2 regulates Hopx+ intestinal stem cell fate and proliferation in a CDK-independent manner. p57Kip2 can repress the transcriptional activity of Ascl2 by participating in the recruitment of a corepressor complex on Ascl2 target gene promoters. Loss of p57Kip2 leads to intestinal stem cell deregulation and dysplasia of the intestinal epithelium.