<p>This study investigates the (3+1)-dimensional Gardner-type equation, which models nonlinear sound wave propagation, using Lie symmetry methods. Unlike many existing studies, which most often rely on restrictive ansätze or special transformations, we employ Lie point symmetry analysis to systematically reduce the governing NPDE into nonlinear ordinary differential equations (NODEs) without assuming a predefined solution structure. Also, conserved quantities are derived through Ibragimov’s theorem and the multiplier method, ensuring methodological complementarity and robustness in constructing conserved vectors such as mass, momentum, and energy. The current results demonstrate how the increase in wave speed along a specific spatial direction increases momentum and energy, while decreases occur along perpendicular directions. The analysis of solutions obtained indicates a link between models and physical interpretation. The study not only obtains new families of exact solutions and conservation laws but also sets a foundation for extending symmetry-based approaches to higher-dimensional and more complex nonlinear wave models.</p>