The problem of a two-dimensional polaron in a magnetic field is retrieved within the framework of an improved variational approximation which sets up a fractional admixture of the strong- and weak-coupling counterparts of the coupled electron-phonon system. The formulation is based on the usage of an adiabatic polaronic wavefunction corrected by a variationally determined perturbative extension enabling the adiabatic ansatz to be extrapolated towards the weak-coupling regime. The trial state derived here accounts for the magnetic field intensity not only in the electron part of the Hamiltonian, but also within the context of the part of the Hamiltonian describing the coupling of the electron to the phonon field.