Aluminum-based metal matrix composites have a wide range of applications in the automotive and aerospace industries due to their high strength-to-weight ratio. They are difficult to manufacture using fusion-based additive manufacturing (FBAM) processes because of solidification problems such as thermal stresses, hot cracks and porosity. Moreover, the formation of undesired phases at high temperature creates anisotropy in the composites. To overcome these problems, promising solid-state additive manufacturing (SSAM) processes such as ultrasonic AM, cold-spray AM, friction stir AM, and additive friction stir deposition have been developed. These solid-state processes introduce a novel concept for AM where material is added layer by layer in the solid state by maintaining the maximum temperature below the melting point of feedstock material. These processes have demonstrated the uniform distribution of reinforcing particles, fine-grained microstructure along with good bonding of layers which can offer improved scope for Industry 4.0 applications. This chapter summarizes progress in the SSAM of composites with an emphasis on aluminum-based composites. In addition, various challenges and future work have been briefly discussed which would be helpful to the researchers and industrialist working in the field of SSAM of composites.