Microalgae are a promising feedstock for renewable biofuel to replace traditional fossil energy. However, one of the major challenges of the commercialization of microalgal biofuels is the efficient and economical harvest of microalgal biomass. Foam flotation, a high-efficiency separation technique originating from the mineral industry, has been adopted recently for potential application in harvesting microalgal biomass. This work critically reviews the principles and current status of microalgal harvesting using foam flotation by summarizing the advantages and challenges as well as the influence of biotic and abiotic factors, analyzing the economic feasibility, and proposing some new techniques as well as future research needs, using an illustrative process flow diagram. This work expands our understanding of microalgal harvesting using foam flotation, which may expedite the research and application of foam flotation in the downstream processing of microalgal biomass for the production of biofuel and bioproducts.