Microbial fuel cells (MFCs), which can directly convert chemical energy in organic matters into electricity, have drawn a lot of attention in the past decades. Recently, MFCs have been integrated with waste-activated sludge (WAS) treatment for recovering energy from WAS. Since 2004, a number of publications regarding this topic have been published. The recent advances in MFCs powered by WAS are critically reviewed. MFC reactor designs, MFC performances, and sludge degradation efficiencies are addressed based on the recent related publications. The challenges and corresponding enhancement measures of MFCs using WAS as fuel are also discussed.