Boron-doped graphene oxide (BG) nanoparticles were synthesized via nanosecond pulsed laser ablation of graphene flakes in ethanol, using boric acid as the boron source and a post-ablation strategy. Structural and elemental analyses (Raman, FT-IR, and XPS) confirmed graphene oxidation and successful boron incorporation. FESEM and HRTEM revealed spherical nanoparticles with an average size of 30-60 nm. Optical studies showed excitation-dependent bluish-green photoluminescence with enhanced intensity and a high quantum yield (5.30 %) due to boron doping, while time-resolved spectroscopy indicated an increased average lifetime (2.54 ns). Biocompatibility studies demonstrated low cytotoxicity toward T24 cancer cells, with boron-rich samples exhibiting particularly high photostability. Efficient cellular internalization and stable emission under biological conditions highlight the potential of BG nanoparticles as safe and effective bioimaging probes.