AbstractAs the downscaling of conventional semiconductor electronics becomes more and more challenging, the interest in alternative material systems and fabrication methods is growing. A novel bottom‐up approach for the fabrication of high‐quality single‐electron transistors (SETs) that can easily be contacted electrically in a controllable manner is developed. This approach employs the self‐assembly of Au nanoparticles forming the SETs, and Au nanorods forming the leads to macroscopic electrodes, thus bridging the gap between the nano‐ and microscale. Low‐temperature electron‐transport measurements reveal exemplary single‐electron tunneling characteristics. SET behavior can be significantly changed, post‐fabrication, using molecular exchange of the tunnel barriers, demonstrating the tunability of the assemblies. These results form a promising proof of principle for the versatility of bottom‐up nanoelectronics, and toward controlled fabrication of nanoelectronic devices.