This paper presents the first swing stabilization control for indoor miniature autonomous blimps (MABs). Indoor MABs are safe to operate in close proximities to humans and can fly for multiple hours, but swing oscillation is commonly observed due to their underactuated design and unique aerodynamic shape. In this paper, we analyze the flight characteristics of indoor MABs, and describe the design of the swing-reducing flight control system in detail. Key mechatronic designs for swingstabilization control are also presented. Experimental results show that the proposed controller can keep the blimp travel at the desired velocity while effectively stabilizing the swing oscillation. The swing-reducing velocity controller is then expanded for station-keeping and waypoint navigation in 3D space.