Fast pyrolysis is an attractive platform technology to convert lignocellulosic biomass into fuels, energy, and other value-added products. However, most of the biomass materials, e.q., forest waste, agricultural waste, energy crops, and municipal solid waste, have low bulk and energy density and are difficult to store, transport and convert. Furthermore, the variations in feedstock composition and particle size among a few other factors all affect fast pyrolysis performance and product quality. Biomass densification, such as pelleting, generates a form of biomass feedstock with high mass and energy density and great homogeneity via blending of different feedstocks, providing unique opportunities to improve feedstock quality for fast pyrolysis. This paper summarizes the basic principles, processes and influencing factors, and the recent developments in both densification and fast pyrolysis fields with special focus on the combination of pelleting and fast pyrolysis. The challenges and perspectives are also provided for the development of an efficient, cost-effective and scalable fast pyrolysis technologies for generating fuels and chemicals.