Luminescent erbium-based inorganic–organic hybrid materials play an important role in many frontier nano-sized applications, such as amplifiers, detectors and OLEDs. Here, we demonstrate the possibility to fabricate high-quality thin films comprising both erbium and an appropriate organic molecule as a luminescence sensitizer utilizing the combined atomic layer deposition and molecular layer deposition (ALD/MLD) technique. We employ tris(N,N′-diisopropyl-2-dimethylamido guanidinato)erbium(III) [Er(DPDMG)3] together with 3,5-pyridine dicarboxylic acid as precursors. With the appreciably high film deposition rate achieved (6.4 Å cycle−1), the guanidinate precursor indeed appears as an interesting new addition to the ALD/MLD precursor variety toward novel materials. Our erbium–organic thin films showed highly promising UV absorption properties and a photoluminescence at 1535 nm for a 325-nm excitation, relevant to possible future luminescence applications.