Photopolymerization is a powerful tool in materials science with many applications, including coatings, adhesives, inks, and 3D printing. Until now, the majority of photoinitiating systems have been suitable only for radical photopolymerization, which automatically excludes the use of light to trigger a great number of polymerization reactions. For instance, the preparation of polyurethanes via photopolymerization from isocyanates remains a real challenge since it requires a catalyst able to mediate nucleophilic substitution reactions. In this context, this study reports the successful synthesis of three new photobase generators based on a thioxanthone chromophore functionalized with a protonated 1,8-diazabicyclo[5.4.0]undec-7-ene as a latent base for the direct synthesis of polyurethanes from commercially available polyols and polyisocyanates. The catalytic activity of the photobase is modulated by introducing different functional groups at the a-position of the carboxylate which act as a photocleavable link between the chromophore and the latent base. A direct correlation between the steric hindrance of such groups and more efficient release of the base is observed by H-1 NMR. DFT studies have been performed to shed some light on the base release mechanism and to further confirm this evidence. To demonstrate their use, the ability of these photobases to mediate the nucleophilic substitution between isocyanates and alcohols has been proven by using bifunctional and trifunctional monomer mixtures by H-1 NMR, FTIR, and rheology experiments. To further exploit the full potential of the thioxanthone-based photobase generators, polyurethane coatings as well as 3D printed figures have been prepared at room temperature by using light as an external trigger.