Embryonic stem cells (ESCs) have the potential to generate virtually any differentiated cell types to establish new models of mammalian development and to create new sources of cells for treating an enormous range of diseases. To elucidate the molecular pathways underpinning the transition from naïve to primed pluripotency cell states, we quantified the dynamic changes in the proteome, phosphoproteome, transcriptome, and epigenome underpinning the transition between these cellular states with high temporal resolution. We observed widespread remodelling of the cell across all regulatory layers, and yet the rate, extent and magnitude of phosphorylation changes exceed those observed on other levels, emphasising a critical role for phosphorylation in this process. Our dynamic phosphoproteomics data reveal that ERK and mTOR signalling branches dominate early and late signalling network activity respectively during the ESC to EpiLC transition. Collectively these data provide insight into the molecular processes underlying naïve and primed states, highlighting numerous potential gatekeeper mechanisms governing ESC pluripotency.