Bambara groundnut (Vigna subterranean), also referred to as Bambara nut or Ground beans, is considered as one of the most important legumes in African countries where it is grown. However, it is one of the neglected crops that needs to be promoted in the current situation as it is a crop that offers many benefits, including being a nutrient-dense grain. It also potentially resilient to challenges that arise due to climate change and soil degradation as it biologically fixes nitrogen (N). This chapter presents a case study of an evaluation of biological nitrogen fixation (BNF) and yields of six Bambara groundnut cultivars. The six cultivars include two released varieties of Makata and Kayera plus four landraces namely Red, Black, Chikope cha Nyani and Khaki. The study was implemented at the Lilongwe University of Agriculture and Natural Resources research farm in the two cropping seasons of 2015/16 and 2016/17. It was implemented in a randomized complete block design (RCBD), with three replicates in each of the two seasons. Results showed that Khaki consistently led to significantly higher (P < 0.05) two year mean biologically fixed N (72.2 kg ha−1), total N yield, number of pods per plant, grain yield and total dry matter yield than the other landraces and varieties except Red that had similar higher amounts of biologically fixed N (71.2 kg ha−1). On the other hand, the other four cultivars produced a range of 45.0 to 52.5 kg ha−1 biologically fixed N. Grain yield ranged from 808 kg ha−1 (Kayera) to 1259 kg ha−1 (Khaki). This study has brought about some new information about the Bambara landraces that exist in Malawi and will be beneficial for breeders in improving varieties of Bambara groundnuts. Further studies should be conducted in different agroecological zones and on different soil types that exist in Malawi.