This study describes the synthesis of cesium carbonate-titanium dioxide (Cs$_2$CO$_3$/TiO$_2$) and boron nitride-cesium carbonate-titanium dioxide (BN/Cs$_2$CO$_3$/TiO$_2$) nanofiber photocatalysts by electrospinning. The nanofiber properties were modulated by varying Cs$_2$CO$_3$ mole percentage. In all prepared nanofibers, the anatase TiO$_2$ structure was the main phase. Cs$_2$CO$_3$ addition in the electrospinning mixture led to the formation of small amounts of rutile phase and decreased the anatase phase crystallinity. The highest photocatalytic activity was observed with the Cs$_2$CO$_3$/TiO$_2$ photocatalyst that included 1.5 mol% of Cs$_2$CO$_3$ Indeed hydrogen production rate (9,853 μmol·g$^{−1}$.h$^{−1}$) was 89.6 times higher than with pure TiO$_2$ nanofibers. Modification of the 1.5% Cs2CO3/TiO2 photocatalyst with hexagonal BN further increased hydrogen production up to 15,823 μmol/g (6 h under visible light). This improvement could be explained by the presence of BN sheets in the BN/Cs$_2$CO$_3$/TiO$_2$ catalyst that improve the separation of the photoinduced electron–hole pairs in TiO$_2$ and increase the specific surface area compared with pure TiO$_2$ and Cs$_2$CO$_3$/TiO$_2$ nanofibers