Disclosed herein are stairstep interposers with integrated conductive shields, and related assemblies and techniques. In some embodiments, an interposer may include: an insulating material having a stairstep structure with a first step surface, a second step surface, and a bottom surface to face a package substrate, wherein a first thickness of the insulating material between the first step surface and the bottom surface is greater than a second thickness of the insulating material between the second step surface and the bottom surface; a conductive signal pathway extending from the first step surface to the bottom surface; and a conductive shield disposed within the insulating material to shield the conductive signal pathway.