This study evaluated the effect of abscised unripe mango fruit meal (AUMFM) in comparison to maize and Samsorg-49 offal on the performance, rumen indices and methane emissions of Yankasa ram lambs. Twelve growing rams with an average weight of 17.33 kg were randomized into three dietary treatments, namely AUMFM, maize offal and Samsorg-49 offal, each at a 30% inclusion level, with four replicates per group. They were fed for 90 days in a CRD. Data collected were analysed using the GLM procedure of ANOVA in SPSS and significant means were compared using DMRT at P<0.05. The results showed that the weight gains of rams fed 30% dietary inclusions of AUMFM (97.25 g/ram/day) and maize offal (104.40 g/ram/day) were statistically similar and higher (P<0.05) than Samsorg-49 offal (81.59 g/ram/day), while the FCR was higher (P<0.05) in Samsorg-49 offal (9.18) compared to maize offal (7.27). However, the dietary inclusion of AUMFM had higher CH4 efficiency (25.05%) compared to maize offal (30.93%) and Samsorg-49 offal (30.82%). Although there were no differences (P>0.05) observed for feed intake, nutrient digestibility, nitrogen utilization and rumen indices among the dietary treatments, the dietary inclusions of AUMFM and maize offal showed increasing tendency to impact nitrogen free extract digestibility (P=0.09), nitrogen retained (P=0.07) and N-retained as a % of intake (P=0.06) compared to the Samsorg-49 diet. In conclusion, 30% inclusion of AUMFM in the diet of Yankasa ram lambs had a weight gain comparable to dietary maize offal, with higher CH4 efficiency compared to both the 30% dietary inclusion of maize and Samsorg-49 offal. This study underscores the importance of exploring the potential of AUMFM as a cheap dietary energy ingredient with a low carbon footprint as compared to the maize and Samsorg-49 offal in the diets of Yankasa ram lambs. Hence, ruminant livestock farmers are encouraged to adopt 30% dietary inclusion of AUMFM for better weight gain compared to Samsorg-49 offal, cheaper cost of feeding, and climate-smart livestock production.