Carbon nanomaterials field-effect transistor (FET)-based electrical biosensors provide significant advantages over the current gold standards, holding great potential for realizing direct, label-free, real-time electrical detection of biomolecules in a multiplexed manner with ultrahigh sensitivity and excellent selectivity. The feasibility of integrating them with current complementary metal oxide semiconductor platform and a fluid handling module using standard microfabrication technology opens up new opportunities for the development of low-cost, low-noise, portable electrical biosensors for use in practical future devices. In this article, we review recent progress in the rapidly developing area of biomolecular interaction detection using FET-based biosensors based on the carbon nanomaterials single-walled carbon nanotubes (SWNTs) and graphene. Detection scenarios include DNA-DNA hybridization, DNA-protein interaction, protein function and cellular activity. In particular, we will highlight an amazing property of SWNT-or graphene-FETs in biosensing: their ability to detect biomolecules at the single-molecule level or at the single-cell level. This is due to the size comparability and the surface compatibility of the carbon nanomaterials with biological molecules. We also summarize some current challenges the scientific community is facing, including device-to-device heterogeneity and the lack of system integration for uniform device array mass production. Keywords: biosensor; carbon nanotube; field-effect transistor; graphene A biosensor is an analytical device that incorporates a biological recognition element in direct spatial contact with a transduction element. This integration ensures the rapid and convenient conversion of the biological events to detectable signals. 1 With the discovery of rich nanomaterials and the development of exquisite nanofabrication tools, such as electron beam lithography, focused ion beam and nanoimprint lithography, new avenues have been opened up in the field of biosensors in the last two decades. 2,3 In particular, researchers around the world have been tailor-making a multitude of nanomaterials-based electrical biosensors and developing new strategies to apply them in ultrasensitive biosensing. Examples of such nanomaterials include carbon nanotubes, 4-13 nanowires, 11,14-21 nanoparticles, 6,22-25 nanopores, 26,27 nanoclusters 28 and graphene. 5,[29][30][31][32] Compared with conventional optical, biochemical and biophysical methods, nanomaterial-based electronic biosensing offers significant advantages, such as high sensitivity and new sensing mechanisms, high spatial resolution for localized detection, facile integration with standard wafer-scale semiconductor processing and label-free, real-time detection in a nondestructive manner.Among diverse electrical biosensing architectures, devices based on field-effect transistors (FETs) have attracted great attention because they are an ideal biosensor that can directly translate the interactions between target biological mole...