Gate-all-around integrated circuit structures having a multi-layer molybdenum metal gate stack are described. For example, an integrated circuit structure includes a first vertical arrangement of horizontal nanowires, and a second vertical arrangement of horizontal nanowires. A PMOS gate stack is over the first vertical arrangement of horizontal nanowires, the PMOS gate stack having a multi-layer molybdenum structure on a first gate dielectric. An NMOS gate stack is over the second vertical arrangement of horizontal nanowires, the NMOS gate stack having the multi-layer molybdenum structure or an N-type conductive layer on a second gate dielectric.