The major aim of this experimental study is to evaluate the engineering properties of ultralightweight foamed concrete produced using the pre-foamed method. Four ultra-lightweight foamed concrete mixtures were designed with the target dry densities of 500, 600, 700, and 800 kg/m3 corresponding to the foam contents of 7.1, 5.3, 4.2 and 2.7%. It is noted that the foam was prepared prior to be used by a foam generator using the foaming agent/water ratio of 1/40. Local materials sourced from Southern Vietnam, including PC40 Portland cement, fly ash, slag, stone powder, superplasticizer, and water were used for this study. All of the ultra-lightweight foamed concrete samples were prepared in the laboratory for the tests of compressive strength, water absorption, dry density, drying shrinkage, and thermal conductivity. Moreover, the microstructure of the ultra-lightweight foamed concrete samples was also observed using a scanning electron microscope. Cost analysis was also performed to further evaluate the potential application of the ultralightweight foamed concrete in real practice. Test results show that foam content affected the engineering properties of the ultra-lightweight foamed concrete samples significantly. The increase in foam content resulted in increasing water absorption and drying shrinkage while decreasing compressive strength, dry density, thermal conductivity, and cost. A poorer microstructure was also observed at the ultra-lightweight foamed concrete samples containing more foam. The ultra-lightweight foamed concrete samples with dry densities ranging from 500 – 800 kg/m3 obtained the compressive strength, water absorption, thermal conductivity, and cost in the ranges of 0.78 – 6.88 MPa, 30.7 – 85.8%, 0.103 − 0.231 Wm/K, and 407000 – 693000 VND/m3, respectively. Thus, properties of the ultra-lightweight foamed concrete samples conformed well to the official Vietnamese standard requirements, except for the D500 sample.