A high efficiency dust controlling gutter broom apparatus comprises a mounting arm, and a gutter broom having a mounting structure and bristles depending from the mounting structure. The gutter broom is mounted via the mounting structure in supported relation on the mounting arm for rotation about a gutter broom axis. A gutter broom motor rotates the gutter broom about the gutter broom axis. A shroud has a roof portion and a wall portion depending from the roof portion. The shroud is mounted in supported relation on the mounting arm such that the roof portion covers at least a rear portion of the mounting structure of the gutter broom and the wall portion covers at least a rear portion of the bristles of the gutter broom. An air-flow precluding member is secured to the gutter broom for rotation therewith, to thereby substantially obstruct air flow through the gutter broom.