Highlights • Residual hemicellulose in cellulose sample favors nanofibrillation. • Non-derivatized holocellulose and cellulose samples produce good quality CNF. • Residual hemicelluloses improve stability of cellulose nanofibers. • Hemicelluloses, especially mannan, improve the mechanical properties of nanopaper. • Low lignin content does not compromise nanofibrillation of cellulose sample. Abstract This paper investigated the impact of the amounts of lignin and hemicelluloses on cellulose nanofibers (CNFs). Birch and spruce wood were used to prepare holocellulose and cellulose samples by classical methods. To better assess the effect of the chemical composition on the CNF performance and simplify the process for CNF preparation, no surface derivatization method was applied for CNF preparation. Increased amounts of hemicelluloses, especially mannans, improved the defibration process, the stability of the CNFs and the mechanical properties, whereas the residual lignin content had no significant effect on these factors. On the other hand, high lignin content turned spruce nanopapers yellowish and, together with hemicelluloses, reduced the strain-at-break values. Finally, when no surface derivatization was applied to holocellulose and cellulose samples before defibration, the controlled preservation of residual lignin and hemicelluloses on the CNFs indicate to be crucial for the process. This simplified method of CNF preparation presents great potential for forest-based industries as a way to use forestry waste (e.g., branches, stumps and sawdust) to produce CNFs and, consequently, diversify the product range and reach new markets. [ABSTRACT FROM AUTHOR]