Assembly of 3D architectures with programmable shape configurations has important applications in broad areas. However, previously assembled 3D architectures are either not reversible or free-standing, limiting their applications and/or functions. We demonstrate a novel reversible self-assembly of soft 3D architectures actuated by the self-folding of smart polymer substrates with programmed geometries. The substrates can reversibly respond to external stimuli to actuate planar origami/kirigami films for self-assembly of 3D architectures and they become parts of final 3D architectures, empowering their reversibility and freedom. The self-assembly process is controlled by origami and kirigami design patterned by direct laser writing. A variety of 3D architectures like “flower”, “rainbow”, “sunglasses”, “box”, “ptramid”, “grating”, and “armchair”, are assembled. The reported self-assembly also shows wide applicability to various soft materials including epoxy, polyimide, laser-induced graphene, and metal films. A micro light-emitting diode (µ-LED) and a flex sensor are integrated with the self-assembled 3D architectures, indictaing the potential applications in soft robotics, wearable electronics, bioelectronics, and microelectromechanical systems (MEMS).