酪氨酸激酶（英语：tyrosine kinase）是在细胞中催化磷酸基团从ATP中转移到蛋白质的酪氨酸残基上的酶，起到调控细胞中信号通路的“开”与“关”。酪氨酸激酶是蛋白激酶中的一类，其它的为丝氨酸/苏氨酸特异性蛋白激酶类。

与酪氨酸激酶相对应的酶是蛋白酪氨酸磷酸酶，负责去磷酸化。由激酶和磷酸酶进行的蛋白的磷酸化与去磷酸化过程对细胞的增殖、分裂与分化的调控非常重要。酪氨酸激酶的一些突变可使其一直处于“活跃”状态，能引起细胞的不受抑制的生长，最终演变为癌症。因此一些酪氨酸激酶抑制剂，如伊马替尼等被作为抗癌药物研发出来。

A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to a protein in a cell. It functions as an "on" or "off" switch in many cellular functions. Tyrosine kinases are a subclass of protein kinase.

The phosphate group is attached to the amino acid tyrosine on the protein. Tyrosine kinases are a subgroup of the larger class of protein kinases that attach phosphate groups to other amino acids (serine and threonine). Phosphorylation of proteins by kinases is an important mechanism in communicating signals within a cell (signal transduction) and regulating cellular activity, such as cell division.