Sphingosine‐1‐phosphate (S1P) is a signalling lipid that regulates many cellular processes in mammals. One well‐studied role of S1P signalling is to modulate T‐cell trafficking, which has a major impact on adaptive immunity. Compounds that target S1P signalling pathways are of interest for immune system modulation. Recent studies suggest that S1P signalling regulates many more cell types and processes than previously appreciated. This review will summarise current understanding of S1P signalling, focusing on recent novel findings in the roles of S1P receptors in innate immunity.