The intricate regulation of transcriptional programs and DNA replication processes in mammalian cells relies on dynamic nuclear protein organization. Our findings revealed a MED1-phosphorylation code orchestrating the dynamics of biocondensates in a cell cycle-dependent manner, demonstrating a previously unknown connection between transcription regulation and cell cycle progression. Our work stands as a pioneering effort, elucidating the impact of cell cycle-dependent phosphorylation signals on the formation and dynamics of nuclear condensates. Additionally, our study lays a crucial foundation for future research endeavors aimed at designing targeted interventions to modulate biocondensate dynamics, offering potential avenues for developing innovative therapeutics in various human diseases, including cancer, neurodegeneration, and infectious diseases.