Nanoparticles serve as fundamental building blocks for nanobiotechnology, especially in several applications in the development of novel (bio)sensing systems. Nanoparticles can be used for modification of the surfaces of (bio)sensing transducers or as optical or electroactive labels to improve different aspects of performance, for example sensitivity, detection limit, multidetection capability, and response stability. Nanoparticles can be integrated into the transducer materials on an individual basis or inside other matrices to ensure the immobilization of recognition biomolecules and/or receptors which are the principal components of the (bio)sensing systems. Incorporation of nanoparticles into optical and electrochemical (bio)sensing systems, including their use in microfluidic based systems has the advantages of enabling the design of robust, easy to use, portable, and cost-effective devices.