Using a modified sol–gel method, LiLa(MoO4)2: Tm3+/Ho3+/Yb3+ phosphors with tailorable up-conversion (UC) emission colors were prepared. Under the excitation of a 980 nm laser diode, up-conversion red and green emissions in Ho3+/Yb3+ co-doped and blue emission in Tm3+/Yb3+ co-doped LiLa(MoO4)2 were observed, respectively. The intensities of the RGB (red, green, and blue) emissions could be controlled by varying concentrations of Tm3+ or Ho3+, and the optimal composition was also determined. In Tm3+/Ho3+/Yb3+ co-doped LiLa(MoO4)2, the UC emission colors could be tuned from blue through white to yellow by adjusting the concentrations of Tm3+ or Ho3+. The UC excitation mechanisms were also investigated based on the power dependence of UC luminescence intensity.