Sustainably produced platform chemicals are increasingly sought after. Fatty acids containing olefinic and hydroxy groups are particularly interesting as platform chemicals for regio-and stereo-selective downstream reactions. Integral membrane fatty acid desaturases can selectively introduce double bonds or catalyze unusual reactions such as acetylenation, conjugation, hydroxylation, and epoxidation. Here, a systematic overview of recent achievements and key literature of integral membrane desaturases is provided in the context of biotechnological potential of the enzyme family. Practical Application: Integral membrane fatty acid desaturases may be the most promising tool to increase the scope of fatty acids as platform chemicals. Plant oil production is well researched and an established sustainable pathway toward high-yield chemicals. In addition, effort is increasing toward creating microbial high-yield oil producers. The current bottleneck is the limited fatty acid species that can be produced at high yields. It is envisioned that future enzyme engineering work will enable the targeted design of desaturases to produce modified fatty acids that follow industry needs. This review provides a systematic overview of the natural diversity and complexity of integral membrane fatty acid desaturases to help researchers expand existing fatty acid production beyond currently utilized fatty acid species.