Catalyzes the formation of diacylglycerol from 2-monoacylglycerol and fatty acyl-CoA. Also able to catalyze the terminal step in triacylglycerol synthesis by using diacylglycerol and fatty acyl-CoA as substrates. Has a preference toward palmitoyl-CoA and oleoyl-CoA. May be involved in absorption of dietary fat in the small intestine by catalyzing the resynthesis of triacylglycerol in enterocytes.