Acetoacetyl CoA is the precursor of HMG-CoA in the mevalonate pathway, which is essential for cholesterol biosynthesis.

It also takes a similar role in the ketone bodies synthesis (ketogenesis) pathway of the liver.

[1] In the ketone bodies digestion pathway (in the tissue), it is no longer associated with having HMG-CoA as a product or as a reactant.

Additionally, it reacts with NADPH-dependent acetoacetyl-coenzyme A reductase, also known as PhaB, in a pathway that produces polyester polyhydroxyalkanoate (PHA).

In addition, they play a significant role in neuronal development during the early embryonic and fetal developmental stages.