Livestock is an important component of mixed crop-livestock farming systems in the Singida Region in Tanzania, directly or indirectly contributing to household income, food security and poverty reduction among rural people in the region. This paper examined the effect of livestock on crop commercialisation and farmers’ livelihoods in the region. The complementarity between crops and livestock in the farming systems of Singida needs to be recognised, enhanced and utilised not only by farmers and livestock keepers, but also by local government authorities and development practitioners.