The members of the RE2Pt6Al15 (RE = Ce–Nd, Sm, Gd–Yb) and RE2Pt6Ga15 (RE = Y, La–Nd, Sm, Gd–Lu) series have been synthesized from the elements via arc‐melting followed by annealing in an induction furnace. Isotypism of Ho2Pt6Al15 with orthorhombic (3+1)D commensurately modulated Sc2Pt6Al15 [Cmcm(α,0,0)0s0, α = 2/3] was observed from single‐crystal diffraction data. The diffraction pattern shows the same satellite reflections pattern as the prototype, therefore the same modulated superstructure was refined. Full ordering of the Pt and Al atoms within the [Pt6Al15]δ– polyanion was observed. The lattice parameters of the averaged hexagonal structure were refined from powder X‐ray diffraction experiments and agree well with previous reports on these compounds. The X‐ray pure polycrystalline samples of both series were studied with respect to their magnetic properties. The susceptibility data of all investigated compounds show experimental magnetic moments close to the free ion values of the RE3+ cations and antiferro‐/ferrimagnetic ordering at low temperatures with Curie temperatures up to TC = 16.8(1) K for Gd2Pt6Ga15. Both, Sm2Pt6Al15 and Sm2Pt6Ga15 show the typical van Vleck type behavior along with antiferromagnetic ordering at a Néel temperature of TN = 4.5(1) K (Al) and ferrimagnetic ordering at TC = 6.5(1) K (Ga). Yb2Pt6Al15 exhibits ytterbium in the trivalent oxidation state, while for Yb2Pt6Ga15 a divalent state of the Yb atoms was observed.