Various tissue-engineered vascular grafts have been studied in order to overcome the clinical disadvantages associated with conventional prostheses. However, previous tissue-engineered vascular grafts have possessed insufficient mechanical properties and thus have generally required either preoperative cellular manipulation or the use of bioreactors to improve their performance. In this study, we focused on the concept of in situ cellularization and developed a tissue-engineered vascular graft with degradable/non-degradable polymer composites for arterial reconstruction that would facilitate the renewal of autologous tissue without any pretreatment. Additionally, these composites are designed to improve the mechanical performance of a small-diameter vascular prosthesis scaffold that is made from a flexible membrane of poly(e-caprolactone) (PCL). The PCL scaffold was reinforced by embedding a tubular fabric that was knitted from polyethylene terephthalate (PET) yarns within the freeze-dried composite structure. Adding this knitted fabric component significantly improved the mechanical properties of the composite scaffold, such as its tensile strength and initial modulus, radial compliance, compression recovery, and suture retention force. Finally, this reinforced composite structure is a promising candidate for use as a tissue-engineered scaffold for a future small diameter vascular prosthesis.