Geopolymer foam concrete (GFC) is created by incorporating pores into geopolymer slurry or mortar. The functional and mechanical properties, such as thermal insulation, compressive strength, and density, are influenced by the characteristics of the pores and the properties of their walls. In chemically foamed GFC, foaming agents mixed with the geopolymer slurry release gases through decomposition or reaction. The interaction between the geopolymer and the generated gas during foaming determines the pore characteristics. Gas pressure within the pores is influenced by the gas generation rate of the foaming agent, while confinement pressure is affected by surface tension, viscous resistance, and the weight of the slurry, with viscous resistance being the most significant factor. The foaming process concludes when equilibrium is achieved between gas and confinement pressures or when the slurry solidifies. Various alkali solutions with Na2O contents ranging from 4–7% and modulus ratios from 1.1 to 1.5 were utilized in the mixture design, and the resulting properties were compared to assess their effects. The GFC’s density, compressive strength, and thermal conductivity ranged from 280.8 to 865.8 kg/m3, 1.10 to 8.13 MPa, and 0.088 to 0.20 W/(m × K), respectively. Test results indicated that a higher gas generation rate and lower slurry viscosity—achieved with increased Na2O content and decreased modulus ratio—led to greater porosity, reduced compressive strength, and lower thermal conductivity.