  The greybody factor of massless scalar fields in the four-dimensional
Schwarzschild spacetime involving an $f(R)$ global monopole is derived. We show
how the monopole parameter and the deviation from the standard general
relativity adjust the greybody factor. We also demonstrate that the effects
from the global monopole and $f(R)$ gravity theory are manifest in the energy
emission rate and the generalized absorption cross section of the scalar
fields.
