Tm3+-doped mixed sesquioxide transparent ceramics are attractive candidates for the generation of robust similar to 2.1 mu m lasers. In this paper, laser-quality Tm:(Lu0.8Sc0.2)(2)O-3 mixed sesquioxide ceramics were shaped for the first time by gelcasting of well-dispersed nanopowders, which were obtained using a modified coprecipitation method. The dispersibility of starting nanopowders was largely improved using alcohol-water solvent. The rheological properties of slurries were optimized for gelcasting. We also investigated the densification behavior of the gel-casted green compacts. In contrast to the dry-pressing route, it was found that gelcasting could yield more homogeneous and transparent ceramics. The optical in-line transmittance of the ceramic rod 12 mm in length was as high as 80.3% at 2090 nm. Upon pumping the ceramic rod by 796 nm diode laser, a 1.88 W CW laser at 2090 nm was acquired with a slope efficiency of 24.6% (with respect to the input pump power).