Current clinical practices to treat large bone defects are primarily focused on the use of tissue transplants or prosthetic implants. Although these procedures have been successful in restoring proper bone function, they are also associated with many long-term complications. Tissue engineering is a multidisciplinary field, which aims to develop biological substitutes to replace damage or diseased tissues through combinations of living cells, bioactive drugs or molecules, and three-dimensional porous scaffolds as an alternative to existing transplants and prosthetic implants. Recently, many tissue engineering approaches using injectable systems have been reported, which are clinically appealing in that cells, drugs, molecular signals, and scaffolds can be delivered to irregularly shaped bone defects in a minimally invasive manner. In this chapter, the challenges and requirements of biodegradable injectable systems for bone tissue engineering are discussed along with a review of recently reported biodegradable injectable ceramics, cell-delivery vehicles, and drug delivery systems.