This paper investigates the slag foaming behavior at 1600 °C using biocoke with 5 and 10 wt % wood pellet additions, along with reference coke. The slag composition remained constant (FeO 29.0 wt %, CaO 35.0 wt %, SiO2 17.0 wt %, MgO 10.0 wt %, Al2O3 9.0 wt %). Fourier transform infrared spectroscopy (FTIR) combined with Raman analyses showed subtle microstructural differences between coke and biocoke containing 5 wt % wood pellets. Conversely, biocoke with 10 wt % wood pellet addition exhibited a less organized microstructure. The dynamic evolution of slag foaming during the experiments was divided into several stages, irrespective of the carbon source used. Evaluation of foaming behavior indicated that applying biocoke with 5 wt % wood pellets significantly improved foaming characters, surpassing those of coke. In comparison, a minor decrease in foaming was noted with biocoke containing 10 wt % wood pellets. Chemical and X-ray diffraction (XRD) analyses revealed that biocoke had no notable impact on the slag composition after the foaming. Both FTIR and Raman spectroscopy identified the variations of Si-related structure in the slag foam samples. Furthermore, Raman spectra were segmented into two parts, representing the slag foam and the remaining carbon source. Eventually, the addition of wood pellets to biocoke can allow for a saving in overall carbon usage compared to conventional sources. The results suggest a practical approach for slag foaming involves utilizing biocoke with 5 wt % wood pellet addition and decreasing its amount by 25 wt % from the initial quantity. Graphical Abstract: (Figure presented.)