AbstractBasic features of obliquely propagating dust ion-acoustic (DIA) solitary waves, and their multidimensional instability in a magnetized dusty electronegative plasma (DENP) containing Boltzmann electrons, Boltzmann negative ions, adiabatic mobile positive ions, and negatively charged stationary dust have been theoretically investigated by reductive perturbation method and small-k perturbation expansion technique. The combined effects of ion adiabaticity, external magnetic field (obliqueness), and negatively charged dust, which are found to significantly modify the basic properties (speed, amplitude, width, and instability) of small but finite-amplitude DIA solitary waves, are explicitly examined. It is also found that the instability criterion and the growth rate of unstable perturbation are significantly modified by the external magnetic field, the propagation directions of both the nonlinear waves, and their perturbation modes. The implications of our results in space and laboratory dusty plasmas are briefly discussed.