Cellulose nanofiber (CNF) films are generally brittle in nature and have poor barrier against moisture. Herein four different types of styrene butyl acrylate latices, one large particle size latex and three nanolatices, were combined with CNF in varying proportions in an attempt to improve the nanocomposite film properties. The influence of latex particle size, and glass transition temperature (Tg) and carboxylation level of nanolatex on the mechanical, water vapor barrier and optical properties of the nanocomposite films was evaluated. Nanolatices improved the strength properties, contrary to large particle size latex, indicating a better network formation between nanolatex and CNF. Both low Tg and low carboxylation level nanolatices increased the toughness of films considerably, by making them flexible. A very low addition level (1 wt%) of low carboxylation level nanolatex, for instance, increased the film toughness by more than 100%. All four latices improved the moisture barrier and light transmittance of films to some extent.