The increased blade lengths for higher efficiency than those used in the current wind farms, particularly in offshore wind turbines, call for further enhancement of the glass fiber composites, which are the dominant structural composites used. The blades are subjected to fatigue loading, such as span-wise fatigue, where fatigue strengths are a limiting factor for blade service life. Usually, the fatigue failure of glass fiber composites occurs due to matrix damage and delamination at the fiber/matrix interface during the early cyclic cycles. Hence, the improvement of matrix-dominant properties of glass fiber composite plays an important role in extending fatigue life. We report herein a method to significantly enhance the mechanical properties of the matrix, and also the fiber/matrix interface properties, which lead to a significant extension of fatigue strengths of blades. We introduce oxygen-free aminated graphene (AG) as a nanofiller in the matrix of the glass fiber composite. The strong covalent bonds formed between the amine (NH2–) groups in graphene and the epoxy groups lead to a connected network to strengthen the matrix and, as such, improve the matrix-dominated properties of composites. We report the matrix-dominated properties and the fatigue performance of the aminated graphene-filled glass fiber composite. The results show an improvement in transverse tensile strength and interlaminar shear strength (ILSS). These lead to a significant enhancement of the fatigue strengths of the glass fiber composites. The results presented herein indicate that using a very small amount of aminated graphene as nanofillers can significantly enhance the mechanical properties, in particular, fatigue strengths, that can extend the blade life significantly.