Let H be a finite-dimensional unimodular pivotal quasi-Hopf algebra over a field k , and let H -mod be the pivotal tensor category of finite-dimensional H -modules. We give a bijection between left (resp. right) modified traces on the tensor ideal H -pmod of projective modules and left (resp. right) cointegrals for H . The non-zero left/right modified traces are non-degenerate, and we show that non-degenerate left/right modified traces can only exist for unimodular H . This generalises results of Beliakova, Blanchet, and Gainutdinov [1] from Hopf algebras to quasi-Hopf algebras. As an example we compute cointegrals and modified traces for the family of symplectic fermion quasi-Hopf algebras.