A microbial fuel cell (MFC) is a promising renewable energy option, which enables the effective and sustainable harvesting of electrical power due to bacterial activity and, at the same time, can also treat wastewater and utilise organic wastes or renewable biomass. However, the practical implementation of MFCs is limited and, therefore, it is important to improve their performance before they can be scaled up. The surface modification of anode material is one way to improve MFC performance by enhancing bacterial cell adhesion, cell viability and extracellular electron transfer. The modification of graphite felt (GF), used as an anode in MFCs, by electrochemical oxidation followed by the treatment with ethylenediamine or p-phenylenediamine in one-step short duration reactions with the aim of introducing amino groups on the surface of GF led to the enhancement of the overall performance characteristics of MFCs. The MFC with the anode from GF modified with p-phenylenediamine provided approx. 32% higher voltage than the control MFC with a bare GF anode, when electric circuits of the investigated MFCs were loaded with resistors of 659 Ω. Its surface power density was higher by approx. 1.75 times than that of the control. Decreasing temperature down to 0 °C resulted in just an approx. 30% reduction in voltage generated by the MFC with the anode from GF modified with p-phenylenediamine.