In light of the current increasing interest toward nanomaterials for concrete technology, it appears that nanocellulose (with its incredible properties) can shape a promising sustainable candidate. This study investigates the influence of a new type of nanocellulose materials, namely, cellulose filaments (CF), on the properties of cement pastes and self-consolidating concrete (SCC). CFs were found to alter mixture rheology and improve its stability because of the filaments’ hydrophilicity. While the compressive strength of CF pastes was adversely affected (because of air entrainment and filament agglomeration), the flexural capacity was increased by up to 25%. In SCC, all measured mechanical properties were enhanced. Strength improvements of up to 16% (in compression), 34% (in splitting tension), 22% (in flexure), and 96% (in energy absorption) were obtained. These improvements were attributed to two effects imparted by CF: nanoreinforcing and internal curing. The former was evidenced by microstructural analysis, while the latter was confirmed by the assessment of autogenous shrinkage, in which CF reduced the shrinkage strains at 7 days by up to 31%. In SCC, CFs also imparted a viscosity-modifying effect, in which the hardened properties were enhanced via improving mixture stability.