The urgent need to address the global energy crisis and dwindling fossil fuel reserves has intensified efforts to develop sustainable energy solutions. This research examines the combustion performance and emission profiles of biodiesel and its diesel blends using a 35 kW industrial burner within a laboratory furnace setup. Two fuels were analyzed: pure biodiesel (B100) and a 50% biodiesel–50% diesel mixture (D50B50). Temperature distributions across the furnace and emission levels during combustion were systematically measured. Findings revealed that both D50B50 and B100 generated higher flame temperatures and substantially decreased carbon monoxide (CO), unburned hydrocarbon (UHC), and soot emissions relative to pure diesel. Specifically, D50B50 demonstrated emission reductions of ~15% (CO), 19% (UHC), and 9% (soot), whereas B100 showed more pronounced reductions of 28%, 36%, and 30%, respectively. Conversely, nitrogen oxide (NOx) emissions rose by approximately 6% and 12% for D50B50 and B100, attributed to biodiesel's inherent oxygen content and increased combustion temperatures. Higher biodiesel concentrations also correlated with elevated exhaust and peak flame temperatures. The study underscores the viability of waste cooking oil biodiesel blends in enhancing combustion efficiency and curbing detrimental emissions, even with a marginal increase in NOx output.