The reuse of waste in construction has been an alternative to minimize the environmental impact and transform waste into raw material. The present study evaluated the replacement of natural sand by fine green foundry sand waste in the manufacture of foam concrete. Different levels of substitution were tested, as well as the amount of foam and the type of curing. The results indicated that the compressive strength ranged from 4.0 to 12.6 MPa, with mixtures with 20% foam and 50% fine green foundry sand waste (FGFSW) presenting results close to 6 MPa. The cementitious matrices presented uniform and distributed pores for mixtures with 20% foam in all levels of FGFSW substitution. The dry and saturated densities varied from 946 to 1743 kg/m³ and from 1244 to 1881 kg/m³, respectively. Thermal conductivity results ranged from 0.28 to 0.53 W/m.K and water absorption ranged from 4.5% to 38.2%. In summary, the study showed that it is possible to use the FGFSW for the manufacture of foamed cellular concrete with technical effectiveness.