To alleviate the shortage of high-quality roughage resources in arid areas, this study aimed to investigate the potential of ensiling sweet sorghum (SS) with aerial parts of licorice (APL) to support sustainable sheep production. Fifty healthy 3-month-old Karakul sheep (20.5 ± 0.87 kg) were randomly divided into five groups and fed with mixed silage diets of SS and APL in ratios of 100:0, 75:25, 50:50, 25:75 and 0:100 (dry matter basis). The measurement period lasted 60 days. The results showed that the sheep consuming 25 SS: 75 APL had the highest average daily gain and the lowest feed conversion ratio, as well as increased serum total protein, albumin, and high-density lipoprotein cholesterol. With increased APL in the diet, rumen pH, the concentration of ammonia nitrogen (NH3–N), the proportions of propionic acid (PA) and butyric acid (BA) linearly increased, while the acetic acid (AA) proportion and the AA/PA ratio linearly decreased. As APL increased in the diet, the Alpha diversity index of rumen bacterial community decreased, while the relative abundance of Proteobacteria, Ruminococcus, Oscillospira, and Butyrivibrio increased. The relative abundance of Oscillospira, Desulfovibrio, Coprococcus, and Bacillaceae_Bacillus was positively correlated with rumen pH, NH3–N concentration, the proportion of PA in rumen fluid (p < 0.05), and negatively correlated with the AA/PA ratio (p < 0.05). Microbial metabolic pathways such as amine and polyamine biosynthesis and secondary metabolite degradation were positively correlated with NH3–N concentration and PA proportion (p < 0.05). In summary, the mixed silage of SS and APL at the ratio of 25:75 effectively improved the growth performance, protein and lipid metabolism, rumen fermentation patterns, and rumen microbial community structure and functional pathways of Karakul sheep. This study provides data supporting the efficient utilization of characteristic feed resources in arid regions.