The interfacial bond strength between a concrete substrate and repair materials plays an important role in the overall performance of a concrete patch repair system. In this paper, patch repair materials made from micro synthetic fibre-reinforced mortar were cast on the surface of a concrete substrate with smooth interfacial texture (as cast) with the aim of investigating the interfacial bond strength as a function of variations in fibre volume fraction without interference from the influence of roughness by surface treatment. The bond strength was determined by an experimental method using slant shear and tensile splitting test. The result showed that the inclusion of micro synthetic fibre increases the bond strength and the magnitude of the increment depends on the fibre volume fraction. The optimum increase of bond strength is found in the mortar with a fibre volume fraction of 0.06%, giving an increase of 40.21% and 48.71% for slant shear and tensile splitting bond strength specimens at the age of 7 days, respectively. Furthermore, tests on micro synthetic fibre-reinforced repair mortar with fibre volume fractions of 0.06% at the ages of 1, 3, 7, and 28 days were conducted to see the development of the bond strength. The slant shear test gives a higher bond strength than the corresponding tensile splitting tests. The smooth interfacial texture between the repair materials and concrete substrate provides adequate adhesion but insufficient friction. This study also established the correlation between slant shear, tensile splitting, and mechanical properties of micro synthetic fibre-reinforced patch repair mortar.