Photo-mediated systems present a highly attractive route for controlling the intracellular delivery of their cargo. Of particular interest, oligonucleotides are a promising class of molecule that are highly versatile for intracellular applications, but lack the necessary in vivo stability on their own. A novel, greener synthetic route to a photocleavable phosphoramidite was developed. The amidite was incorporated into an oligonucleotide by solid-phase synthesis, which was covalently linked to UV-emissive lanthanide-doped upconverting nanoparticles (UCNPs) through click chemistry. The nanosystem was fully characterized for energy transfer dynamics between the photocleavable oligonucleotide and UCNP using 976 nm excitation. The practical and green synthesis of the photocleavable phosphoramidite, combined with the fundamental understanding of the interactions between the oligonucleotide and nanoparticle during excitation paves the way for future in vitro applications for this type of system.