Poly[(dimethyl-methylvinyl)siloxane] copolymer (PMViS) was prepared through the anionic polymerization of hexamethylcyclotrisiloxane (D3) and 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (D4Me,Vi) at 0 °C for 24 h. Poly[(dimethyl-methylvinyl)siloxane]-phosphine oxide (PMViSPO) was prepared by adding phosphorus oxychloride (POCl3) to PMViS dissolved in toluene at 0 °C under a nitrogen atmosphere. Cadmium selenide (CdSe) was prepared by reacting cadmium oxide (CdO), tetradecylphosphonic acid (TDPA), and trioctylphosphine oxide (TOPO) at 300 °C, after adding a solution of dispersed Se to the mixture of tributylphosphine (TBP) and trioctylphosphine (TOP). The CdSe-polyorganosiloxanephosphine oxide (CdSe-SPO) adduct was synthesized by adding PMViSPO to the CdSe preparing solution. CdSe and CdSe-SPO were characterized by UV-Vis spectroscopy and photoluminescent (PL) spectroscopy. α, ω-Vinyl polydimethylsiloxane (VPMS), used as a base resin, was prepared from the equilibrium polymerization of D3 and 1,1,3,3-tetramethyl-1,3-divinyldisiloxane (MVS) at 90 °C for 2 h. α, ω-Hydrogen polydimethylsiloxane (HPMS), as a crosslinker, was prepared from the equilibrium polymerization of D3 and 1,1,3,3-tetramethyldisiloxane (MS) at 90 °C for 2 h. Liquid polyorganosiloxane rubber (LSR) composites containing the CdSe/CdSe-SPO adduct were fabricated from the compounding of VPMS, HPMS, and the CdSe/CdSe-SPO the adduct with a Pt catalyst. Through transmission electronic microscopy (TEM) analysis, the morphology of the LSR composites was confirmed to be that of CdSe nanoparticles with photoluminescence characteristics uniformly dispersed in the LSR.