The hot-injection route is a well-established approach to generating colloidal, monodisperse quantum dots (QDs) and other nanoparticles (NPs) in an organic solvent. Shape control represents the next stage in NP synthesis chemistry, as it has already been demonstrated for a number of QD compositions. However, it remains quite challenging to synthesize NPs that are uniform in both shape and dimension, as in the case of CdSe tetrapods. Improved synthesis methods would increase the yield of desired nanoshapes and eliminate the need for selective precipitation. For the first time, we report that quaternary alkylammonium compounds (or quats) can promote the formation of faceted NPs. Their use in hot-injection synthesis chemistry provides a new means to CdSe tetrapods with surprisingly high shape and dimensional uniformity (>90% selectivity towards the tetrapod shape). The use of quats eliminates both selective precipitation as a purification step and the more costly alkylphosphonate ligands for inducing nonspherical shapes, and introduces the prospect of nanoparticle shape control through ligand–nanoparticle charge interactions. This new synthesis route offers the important advantages of greener chemistry and scalability, which could further the development of tetrapod-based photovoltaic and electronic devices