磷酸化酶激酶（英语：Phosphorylase kinase），是催化磷酸化酶的两种变构形式（磷酸化酶a及b）转换的酶。在ATP存在下，催化无活性的磷酸化酶b的磷酸化，使成为有活性的磷酸化酶a。

EC 1.1/2/3/4/5/6/7/8/9/10/11/12/13/14/15/16/17/18/19/20/21/22  · 2.1/2/3/4/5/6/7(2.7.10/11-12)/8/9  · 3.1/2/3/4(3.4.21/22/23/24)/5/6/7/8/9/10/11/12/13  ·

Phosphorylase kinase (PhK) is a serine/threonine-specific protein kinase which activates glycogen phosphorylase to release glucose-1-phosphate from glycogen. PhK phosphorylates glycogen phosphorylase at two serine residues, triggering a conformational shift which favors the more active glycogen phosphorylase “a” form over the less active glycogen phosphorylase b.