The underlying mechanism of ovulation is of great interest for the development of safer non-hormonal female contraceptives. Ovulation is triggered by the luteinising hormone (LH) surge and a key determinant for ovulation is the LH-induced transcription factor progesterone receptor (PGR). This study sought to identify the effect of the LH surge and PGR on genomic reprogramming in granulosa cells in order to reveal critical mechanisms specific to ovulation. RNA-seq and ATAC-seq of mouse granulosa cells identified large-scale shift in global chromatin accessibility and transcription profile in response to LH-stimulus. Differential analysis of transcription factor binding motifs at open chromatin sites identified two distinct suites of transcription factors that were active before and after the LH-stimulus. Importantly, the canonical binding motif for PGR and other NR3C steroid receptors (GR, AR, MR) was more enriched in regions with reduced chromatin accessibility after LH, whereas motifs for RUNX1 and other transcription factor families were highly enriched among chromatin regions with LH-induced accessibility. This supports our previous demonstration of tissue-specific PGR action through non-canonical motifs, in which ChIP-seq showed that PGR preferrably binds non-canonical motifs corresponding to other transcription factor families in a tissue-specific manner. Comparative ChIP-seq analysis revealed overwhelming mutual chromatin binding between PGR and RUNX1 in granulosa cells, especially at ovulatory gene promoters. Proximity ligation assay also confirmed PGR/RUNX1 physical protein-protein interaction. Finally, we showed through ATAC-seq and RNA-seq of wildtype vs PGR knockout mice that PGR was required to actively enable chromatin accessibility at selective target gene promoters. Overall, we have generated comprehensive maps of epigenomic and transcriptional changes in granulosa cells during ovulation, which provides further understanding of the specialised PGR mechanism in controlling ovulation. Importantly, we showed that direct PGR/RUNX1 interaction is critical for the unique PGR-governed ovulatory network, for which ovulation-targeting novel contraceptives can be designed.