Additive manufacturing (AM), also known as layer-by-layer manufacturing or 3D printing, finds a unique niche in materials processing/fabrication technology to fabricate various complex structures with excellent mechanical, thermal, chemical, and physical properties. In recent years, with the advent of technology, it has become possible to fabricate stimuli responsive smart materials and structures (SRSMS) using AM, thus demonstrating their applications in micro-/nano-electromechanical systems (M/NEMS), energy harvesting, robotics, and biomedical engineering. The manufacturing of SRSMS falls under 4D printing, where change in the printed configuration of the material when subjected to external stimuli over time is evident. Although much has been reported about SRSMS including their synthesis and fabrication and structural and functional properties, much less is known about their applicability at commercial scale. In the same vein, 4D printing for SRSMS, particularly shape memory alloys (SMA) and shape memory polymers (SMPs), is expected to create a major impact on product design and manufacturing transiting from static to dynamic structures. In view of this, the present chapter provides comprehensive insights into SRSMS fabricated via AM (or 4D printing) along with the underlying stimuli responsive mechanisms and integrated functionalities. We classify AM SRSMS according to the material (i.e., polymer and alloys), fabrication process, and stimuli response. At the end, we consider the present challenges and key issues in AM SRSMS comprehensively that can be addressed in near future to accelerate the design and development process of SRSMS.