<p>Smoothed finite element limit analysis (SFEMLA) has shown high efficiency and accuracy for geotechnical stability evaluations, yet its conventional use on continuous media makes it difficult to treat discontinuities at material interfaces. This paper proposes an upper-bound discontinuous node-based smoothed finite element (D-NS-FEM) formulation that admits velocity discontinuities. Velocity jumps are introduced by a node-to-node construction, with smoothing domains split at interface nodes, and the associated flow is enforced on the node-based smoothed strain rate field. The interface is discretized as zero-thickness segments, and its effect is represented via local non-negative auxiliary variables and algebraic constraints tied to node pairs. Bulk and interface contributions are then handled consistently within a single second-order cone programming (SOCP) formulation solved using a primal–dual interior-point method. Numerical analyses of representative geotechnical problems, together with cross-method comparisons and a mesh-refinement study, verify the effectiveness and reliability of this method. The results further show that explicitly modelling interface discontinuities and their shear strength captures the mechanics at soil–structure interfaces and significantly influences failure mechanisms and ultimate bearing capacity, providing a practical tool for high-fidelity stability analyses under complex interface conditions.</p>