Though bitter white lupin (Lupinus albus L.) is a traditional crop in Ethiopia, sweet lupins are new to the country. As a result, the nutritional value of low-alkaloid lupins has not been evaluated under Ethiopian conditions. Crude protein, amino acid and alkaloid contents of 16 cultivars of three annual lupin species grown in four lupin growing locations (Merawi, Finoteselam, Kossober-1 and Kossober-2) of Ethiopia were evaluated. Location × cultivar interaction was a significant source of variation for all traits (p < 0.0001). In all locations, blue entries had either similar (p ≥ 0.0584) or higher (p ≤ 0.0235) forage crude protein content than the Local Landrace, white group and yellow entry. Compared with the Local Landrace, white and blue entries, the sole yellow entry had higher (p ≤ 0.0148) seed crude protein content at all locations except at Kossober-2, where it had similar (p = 0.8460) crude protein content as white entries. The Local Landrace had the highest forage and seed alkaloid contents. However, sweet blue Vitabor and Sanabor entries had the lowest forage and seed alkaloid contents, respectively. Low alkaloid and higher crude protein contents of sweet lupins grown in Ethiopia show the possibility to use sweet lupin forage and seeds as cheap home-grown protein source for livestock feed and human food in the country. However, for more reliable information, the laboratory results need to be verified by animal and human evaluations of the crop.