Due to hierarchical structure of cellulose, its building blocks known as "cellulose nanowhiskers" (CNW) have raised a great deal of research interest over the last decades. Natural affinity of CNW for self-assembly and structural anisotropy allow them to orient under external forces. This book chapter provides a review on the major developments in fabrication techniques of CNW alignment in polymers. First, we will present self-assembly phenomenon of CNW in aqueous medium. Following this, the book chapter will focus on discussion of major strategies reported in the literature on aligning CNW in polymer by external forces: mechanical and by applying electric and magnetic fields. Further, the chapter highlights recent developments in cellulose composite fibers and aligning CNWs by electrospinning and wet-spinning techniques. As insights are gained into CNW reinforcement mechanisms and processing options, future research directions and potential applications are anticipated. These potential application areas will be briefly introduced as well.