Seismic–tectonic activity and sedimentary instability processes can generate submarine landslides that seriously damage seafloor infrastructures and generate large destructive tsunamis if the slide volume is high (more than 1 km3). Sedimentary instability had resulted in a submarine mass failure (SMF) along the North West Borneo Trough (NWBT). This paper presents numerical simulations for a potential landslide tsunami triggered by a SMF in NWBT by a combination of TUNA-LS and TUNA-M2. TUNA-LS simulates landslide tsunami generation based upon an empirical formulation for landslide tsunami initialization. TUNA-M2 solves the 2-D non-linear shallow water equations for simulating tsunami propagation, using tsunami initial conditions calculated by TUNA-LS as input. This landslide tsunami is potentially destructive, with source trough maximum wave height of 120 m. The waves in the front propagate forward in the primary dominant slide direction due northeast. Sabah, Brunei and Sarawak are located in the direction perpendicular to this primary dominant propagation direction. Hence the secondary waves travel southeast towards Sabah, southwest towards Brunei and Sarawak. Simulated offshore wave heights at 50 m depth may reach 15 m to 20 m. Run-up wave heights may exceed 45 m to 60 m depending on locations, exposing communities to extreme hazards.