This article presents a simple thermodynamic model for branched polyolefin systems in the framework of the PC-SAFT equation of state. The physical properties of the polymeric material can be tailored to a customer's specific needs by the choice of the a.-olefin comonomer and the adjustment of its content in the chain. The model efficiently captures the effect of chain branching, comonomer type, and branching density on the phase behavior of polyolefin solutions. Since few adjustable parameters are required, it can be applied to systems for which little experimental data is available. The model parameters follow sensible trends, demonstrating its robustness for extrapolations and parameter prediction. Finally, the simple formulation facilitates its incorporation into commercial software for phase equilibria calculations.