We hereby report a new method of making carbon nanotube (CNT) nanocomposites with one of the most abundant bio-based polymers (cellulose as a matrix). This is done by the assembly of CNTs in cellulose nanofibrils (CNFs) colloidal suspensions in water without any surface modification on CNTs or using surfactant solutions. This gives the capability to add the functionality of the CNTs to cellulose structures without alteration on the pristine CNT structure. Another important issue is the ability to use CNFs themselves as building blocks of various structures such as multifunctional aerogels and microfibers. Moreover, CNFs as well as CNF–CNT hybrids can be transferred into gels and arrested structures in relatively low concentrations. Then, this gel transitions can be done inside the microfluidic channels after hydrodynamic alignment of the nanoparticles. So the aligned particles are arrested in the gel form with high Herman orientation factor that results in high strength and conductivity of the microfibers in the fiber direction. Another important application of these gels is in the formation of aerogels with very low density, relatively high modulus, and conductivity. These aerogels can be formed via ice-templating the gels with a known concentration and density. This assembly opens a new route in CNT nanocomposites. Such conductive and strong composite structures can be used in various applications including sensors, electronic textiles, supercapacitors, etc.