We report on the first mode-locked thin disk laser based on Yb:LuScO(3). This new mixed gain material combines the emission peaks of two sesquioxides, leading to a gain bandwidth of more than 20 nm. We achieve 7.2 W average output power in 227-fs pulses, which is shorter than for any previous ultrafast thin disk laser. The output power was limited by a growth defect near the center of the thin disk.