A display device with narrowed frame border and a manufacturing method thereof are provided. The display device includes a backlight module, an optical film, and a display panel. The backlight module includes an outer frame and a light source module. The outer frame has a bottom plate and a sidewall connected to the bottom plate, and the light source module is disposed in the outer frame near the sidewall. The optical film is disposed on the backlight module and covers the light source module. One side of the optical film protrudes outside from the sidewall and is bent to attach a portion of the sidewall. The display panel is disposed on the optical film opposite to the backlight module.