Klein-Gordon (KG) particles in cosmic string rainbow gravity spacetime and a uniform magnetic field are studied in the context of the so called, metaphorically speaking, positiondependent mass (PDM) settings. We show that the corresponding KG-equation collapses into a two-dimensional radial Schrödinger-Coulomb like model. The exact textbook solution of which is used to find the energies and wave functions of KG-Coulombic particles (both constant mass and PDM ones). In so doing, we consider, with y = E/EP , four pairs of rainbow functions: (a)(d) g 0 (y) = (e ǫy − 1)/ǫy, g 1 (y) = 1. Interestingly, we observe that the first pair in (a) introduces the Planck energy Ep as a maximum possible KG-particle/antiparticle energy value.