The present disclosure relates to display brightness control apparatuses and electronic devices. The display brightness control apparatus can be applied to a display panel. The display panel includes a thin film transistor unit and a light emitting unit. The display brightness control apparatus includes: a detector, which includes a plurality of thin-film transistors in the thin-film transistor unit and is used for outputting a detection current according to the brightness of ambient light; and a controller electrically connected to the detector and used for controlling the luminous brightness of the light-emitting unit according to the detection current. The detector is realized by means of the thin-film transistors, and is arranged inside the thin-film transistor unit of the display panel. The photosensitive characteristic of the thin-film transistors is used to detect the brightness of the ambient light.