A new and distinct Buddleia cultivar named ‘SMNBDBT’ is disclosed, characterized by a compact plant habit that is dense, round and outwardly spreading. Plants have an overall height of less than two feet. Stems are thick and chunky with short internodes, leaves are coriaceous. Plants are cold-hardy and produce abundant panicles of purple flowers. The new variety is a Buddleia, normally produced as an outdoor garden or container plant.
