The ability to remodel lipid metabolism under changing conditions is pivotal for cellular functionality and homeostasis. Here, we characterize the regulatory landscape of phosphorylation-based signaling events across the life cycle of Saccharomyces cerevisiae and determine its impact on the regulation of lipid metabolism. Our data show that 50 lipid metabolic proteins are differentially phosphorylated as cells transit between different physiological states. To identify functional phosphosites, we devised a strategy where multiple phosphosites are simultaneously mutated into phosphomimetic or phosphodeficient alleles and mutants are phenotyped by in-depth lipidomics flux analysis. This uncovers functional phosphosites in the phosphatidate cytidylyltransferase Cds1, the phosphatidylserine synthase Cho1, and Fas2, the α-subunit of the fatty acid synthase (FAS) complex. Furthermore, we show that the fatty acyl chain length produced by FAS is governed by phosphorylation. Overall, our work demonstrates a vital role for phosphoregulation of lipid metabolism and provides a resource to investigate its molecular underpinnings.