Bragg reflectors (BRFs) are essential elements in optical telecommunication and sensing applications. Their miniaturization down to the sub-micron scale has been achieved in silicon-on-insulator chips. However, their tunability is limited only to thermal tuning. In order to achieve a faster and more practical tunability operation, here we report on electro-optically tunable BRFs with ∼14 dB signal filtering on a lithium-niobate-on-insulator platform, while keeping sub-micron cross-sections. Due to the lithium niobate electro-optic properties and the chosen electrodes configuration, a Bragg tunability coefficient of 23.37±0.55 pm/V is achieved, which enhances ∼33 times the tunability performance of state-of-the-art BRFs.