Molecular signaling pathways are crucial for cellular function and communication. In order to work properly, the pathways must be sensitive, adaptable, and tunable to specific stimuli and situations. These essential qualities are made possible by intrinsically disordered proteins (IDPs). IDPs can’t fold into stable, defined structures on their own, but many IDPs can gain at least some structure when they bind with specific partners. These and other interactions change the IDPs’ conformations to enable specific and reversible binding, giving the signaling pathways the sensitivity and flexibility they need to function correctly. Algorithms and other computational tools can help identify IDPs and predict their functions. So far, such tools have revealed that IDPs are pervasive in all kingdoms of life. In addition, they’ve shown that IDPs help relay signals from diverse stimuli, such as ions, lipids, proteins, chemicals, and environmental cues in every category of cell signaling pathway and at every step. Given the pervasiveness of IDPs, it’s likely that additional mechanisms have yet to be discovered, emphasizing the importance of continued research.