Unipolar may refer to:
- Unipolar depression or unipolar disorder: a state of intense sadness, melancholia or despair that has advanced to the point of being disruptive to an individual's social functioning and/or activities of daily living
- Unipolar encoding, a line code
- Unipolar generator, a DC electrical generator in which the magnetic field has the same polarity at every point, so that the armature passes through the magnetic field lines of force continually in the same direction
- Unipolar induction, also known as homopolar generator
- Unipolar motor, a type of small DC electric motor commonly found in small, portable cassette players
- Unipolar neuron, a neuron with a single neurite, round body and with different segments that serve as superficial receptors or terminals
- Unipolar transistor, alternate name for a field-effect transistor, which differs from a bipolar transistor in that only one type of charge carrier is involved in its operation
- Unipolarity, one form of polarity in international relations