The efficient excitation of Er3+ ions through contact with Si nanoparticles (NPs) is demonstrated. A nanostructured doping process has been developed that leads to contact between Si NPs formed in situ and optically-active Er3+ ions embedded in Al2O3. This is achieved by independent and consecutive deposition of the dopants and matrix. The Si NP–Er3+ contact regime enhances the probability of efficient interaction due to the local spatial overlap of the electronic states of the Er3+ and of the Si NP exciton, enabling energy transfer by interband exciton recombination. This leads to up to 53% of the Er3+ ions being excited in as-deposited films.