Porous pure SnO₂ nanofibers (NFs) and La₂O₃ nanoparticles (NPs)-embedded porous SnO₂ NFs were successfully synthesized via electrospinning followed by calcination. These materials were systematically evaluated as gas-sensing elements in metal-oxide-semiconductor (MOS) sensors. The La₂O₃ NPs embedded in porous SnO₂ NFs demonstrated superior gas-sensing performance compared to pure SnO₂ NFs. Specifically, the incorporation of La₂O₃ resulted in a 12-fold enhancement in gas-sensing response towards ethanol, significantly improving both sensitivity and selectivity by tuning the carrier concentration and modifying oxygen deficiencies and chemisorbed oxygen levels. Thus, La₂O₃ NPs embedded in SnO₂ NFs present a promising strategy for the development of high-performance ethanol gas sensors.