Poly(vinyl alcohol) (PVA) foams are advantageous for their biocompatibility and high cost/performance ratio. However, their processibility and comprehensive properties are difficult to achieve. Herein, we report an eco-friendly strategy for preparing PVA foams with improved mechanical properties and thermal stability by constructing a 3D hydrogen-bond (H-bond) network among PVA, lignosulfonic acid (LA), and water. The influences of foaming parameters and LA content on the foaming process and foam structures were investigated. Compared to PVA foam, PVA-LA foam showed improved cell morphology, higher glass transition temperature, and better compressive properties because of the strong H-bond interaction between PVA and LA. The H-bond interactions between LA and water also improved the thermal processing stability of the composite by depressing water evaporation during processing. Furthermore, the additives employed, LA, and water are eco-friendly. It is therefore believed that this work will provide a sustainable and facile strategy for fabricating PVA-based composite foam.