This paper describes the complete implementation of an efficient FPGA in quantum-dot cellular automata (QCA). FPGAs are reconfigurable digital devices which are extensively used in a wide range of industry applications. QCA is a promising nanotechnology able to overcome the limits of current CMOS technology. QCA technology consists of a group of cells which, when combined and arranged in a particular way, are able to perform computational functions. QCA technology transfers information by means of the polarization state of various cells in contrast to traditional computers, which use the flow of electrical current to transfer information. We propose an area efficient 4×1 multiplex-based Configurable Logic Block (CLB). We also propose a novel routing technique that is able to connect CLBs located at three different range groups. The proposed CLB and routing elements can be externally programmable by the user, giving rise to the desired digital circuit. We present QCADesigner simulation results for a 2×2 CLB FPGA.