Horizontal Al/SiO2/Si/SiO2/Al nanoplasmonic slot waveguides with the SiO2 width at each side of ∼15 nm and the Si core width of ∼136–43 nm were fabricated using a fully silicon complementary metal-oxide-semiconductor compatible technology. The propagation losses were measured to be ∼1.07–1.63 dB/μm at the telecommunication wavelength of 1550 nm, in agreement with those predicted from numerical simulation. A simple tapered coupler with length of ∼0.3–1 μm provides a high coupling efficiency of ∼-0.6–-1.5 dB between the plasmonic waveguide and the conventional Si dielectric waveguide. The plasmonic slot waveguide can achieve a low-loss ultracompact bend. A direct 90° bend was demonstrated to have the pure bending loss as low as ∼0.2–0.4 dB. The losses of propagation, coupling, and bending depend weakly on wavelength in the c-band. These results demonstrate the potential for seamless integration of functional plasmonic devices in existing silicon electronic photonic integrated circuits.