A diode-pumped Kerr-lens mode-locked laser generating 25 fs pulses at 1080 nm is demonstrated with an Yb3+-doped compositional mixed calcium aluminate crystal. The Yb:Ca(Gd,Y)AlO4 laser, which operates at a repetition rate of 65.6 MHz via soft-aperture Kerr-lens mode-locking, is pumped by a spatially single-mode, fiber-coupled diode laser. To the best of our knowledge, this is the first Kerr-lens mode-locked laser that utilizes an Yb3+-doped compositional mixed calcium aluminate crystal as the gain medium.