  In this work, we study a constant-roll inflationary model in the Palatini
formalism using modified gravity. Here our action consists a non-minimal
coupling of a scalar field $\phi$ with Ricci scalar $R$ in a general form of
$f(R,\phi)$. Using Palatini approach, we write its equivalent scalar-tensor
form in the Einstein frame and then apply the constant-roll condition in the
equation of motion for the inflaton field. Later the tensor-to-scalar ratio and
the spectral index are calculated using the slow-roll parameters and the
results obtained are matched with the Planck 2018 data. We found that the
results agree nicely with the observations within the parameter regime under
consideration.
