Laser direct-write (LDW) methods offer the rapid, on-demand, and high-resolution patterning of a variety of nanocrystals (NCs). Out of the many LDW methods, the laser-induced modification method is an attractive method as NCs can be directly patterned on polymers without supplementary preparation steps. Previously, it has been indicated that the laser irradiation of polydimethylsiloxane results in composite structures composed of graphitic carbon crystals (GCs) and silicon carbide NCs (SiC-NCs). However, material properties distinctive of SiC-NCs have not been reported for the resulting structures owing to the low formation content relative to those of GCs. In this study by utilizing a high-repetition femtosecond laser, we demonstrate the controlled formation of GCs and SiC-NCs to achieve a composite structure exhibiting a measurable semiconducting behavior for the first time. Moreover, photoluminescence emissions distinctive of fluorescent molecular-sized SiC-NCs were observed from the resulting structures. The presented results will trigger a wave of ideas utilizing ultrashort-pulsed lasers for the laser-induced modification of polymers toward the fabrication of a wide range of electronic and photonic devices, such as memory storage devices, photovoltaics, and optical sensors.