<p>Freeze–thaw (F–T) cycles experienced by rock structures in cold regions are unidirectional, with heat transfer from the external environment to the interior of the rock mass. Unidirectional F–T cycle tests were conducted on carbonaceous slate with a clear bedding structure to investigate the frost deformation characteristics of transversely isotropic rocks. The following results were obtained: (1) the bedding structure strongly influenced the uneven frost heave of transversely isotropic rocks. As the angle between the F–T direction and the bedding surface increases, frost deformation in the parallel F–T direction becomes more pronounced compared to the vertical direction, resulting in more significant uneven frost heave behavior in the slate. Uneven frost heave nearly vanished when the F–T direction was parallel to the bedding surface. (2) Frost deformation in slate was primarily elastic. Under F–T conditions, cumulative plastic deformation damage occurred in the vertical bedding direction, while structural damage was less significant in the parallel bedding direction. (3) The bedding angle had a significantly greater impact on the uneven frost heave coefficient than the temperature gradient. The uneven frost heave coefficient of slate was determined under unidirectional F–T cycles with bedding angle (0°–90°), and temperature gradient (0.626–1.875&#xa0;°C/cm). This study provides essential parameters for calculating frost heave force considering uneven frost heave in transversely isotropic rockworks in cold regions.</p>