In the present paper, NaLa(WO₄)₂ microcrystals with diverse morphologies, sizes and dimensions have been synthesized via a mild and controllable hydrothermal process using polyvinylpyrrolidone (PVP) as surfactant. The phases, morphologies, sizes, and photoluminescent properties of the as-prepared products were well characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra, respectively. The results indicate that the phase, morphology, and size of the NaLa(WO₄)₂ microcrystals can be tuned in a controlled manner by altering the amount of PVP, pH value of the initial solution, and the reaction time. The crystal growth was thoroughly investigated, and a possible formation mechanism was proposed. It is expected that the synthetic strategy can be extended to controllable synthesis of other types of microcrystals as well. Upon ultraviolet (UV) excitation, the NaLa(WO₄)₂:Ln³⁺ (Ln = Eu, Tb) microcrystals exhibit bright red (Eu³⁺, ⁵D₀ → ⁷F₂) and green (Tb³⁺, ⁵D₄ → ⁷F₅) luminescence. The dependence of NaLa(WO₄)₂:Tb³⁺ luminescence intensity on different morphologies has been investigated in detail. Furthermore, the up-conversion (UC) luminescent properties as well as the emission mechanisms of NaLa(WO₄)₂:Yb³⁺/Ln³⁺ (Ln = Er, Tm, Ho) microcrystals were systematically investigated, which show respective green (Er³⁺, ⁴S_3/2,²H_11/2 → ⁴I_15/2), blue (Tm³⁺, ¹G₄ → ³H₆) and yellow (Ho³⁺, ⁵S₂ → ⁵I₈) luminescence under 980 nm NIR excitation.