Recently, carbon nanotube (CNT)-based devices have been extensively utilized for various cellular applications, including neural-signal amplifi cation, [ 1 , 2 ] cancer therapeutics, [ 3 ] and tissue engineering. [ 4 ] For those applications, it is often crucial to control the location and direction of cell growth on CNTs while mimicking an in-vivo-like cellular environment to retain in-vivo-like cellular activity. Several research groups have reported that bulk CNT substrates can support cell adhesion, growth, and differentiation. [5][6][7][8] CNT patterns were also reported to induce the selective growth of neurons and human mesenchymal stem cells (hMSCs). [ 9 , 10 ] However, the effects of CNTs on cells are still controversial and the underlying mechanism for selective cell adhesion and growth is still obscure. In this Communication, we report a study of the role of extracellular matrix (ECM) proteins, such as fi bronectin (FN), in CNT-cell interactions and propose FN-CNT hybrid nanostructures as an effi cient means for cell-growth control. In this work, we fi rst investigated the adhesion properties and conformational change of FNs on the CNTs via immunofl uorescence and force-spectroscopy study. FNs exhibited a strong affi nity to CNTs and maintained a high binding capability to biomolecules even after being adsorbed onto the CNTs. Moreover, the results of our force-spectroscopy-based protein-unfolding experiment confi rm that FNs maintained their native structures on the CNTs. FN-CNT hybrid nanostructures had a stronger affi nity to cells than conventional surfaces, such as FN-coated glass. Importantly, cells formed focal adhesion and grew selectively on the FN-CNT hybrid nanostructures, indicating that the selective growth of cells on