Abstract: A new magnetic carbon nanotube (mCNT) biosensor ink (mbio-ink) that utilizes immobilized capture agents to detect specific target analytes via a simple current response method is presented here, expanding the applications of magnetic carbon nanotubes as biomolecule-sensing nanomaterials. The employment of a magnetic field to print the mbio-ink into electrically conductive networks facilitates its integration with an external circuit via the use of a simple electrode system. When the sensor is connected to an external power source, the reduction in current, caused by an interaction between the capture agents and target analyte, is detected. The rapid detection technique and generic benchtop fabrication method allows for scale up, while the small volumes required and magnet independent electrical measurements renders the mbio-ink attractive for drug screening and disease detection applications.