The plasmon-exciton interaction mechanisms in CdS–Au colloidal quantum-confined plexcitonic nanorod heterostructures have been studied by transient absorption spectroscopy. Optical excitation of plasmons in the Au tip leads to hot electron injection into the CdS rod with a quantum yield of ∼2.75%. This finding suggests the possibility of further optimization of plasmon-induced hot electron injection efficiency through controlling the size and shape of the plasmonic and excitonic domains for potential light harvesting applications.