Ordered mesoporous silicas with cylindrical pores of diameter ~10 and ~15 nm (SBA-15) and spherical pores of ~15 nm (FDU-1) were synthesized and atom transfer radical polymerization (ATRP) of acrylonitrile, 2-(dimethylamino)ethyl methacrylate, styrene and methyl methacrylate initiated from their surfaces was studied. The surface-initiated ATRP allowed us to introduce a controlled amount of uniform polymer chains in nanopores of diameter as low as 10 nm. In some cases, the polydispersity index of the polymer graft was only about 1.1, which is very low for a polymer obtained through surface-initiated polymerization. In cases of the surface-initiated ATRP in cylindrical and spherical mesopores of diameter ~15 nm, it was possible to introduce a significant loading of polymer without making the mesopores inaccessible. The surface-initiated ATRP in nanopores can be optimized to achieve very good control over the uniformity of the polymer graft. This work demonstrates new opportunities in the synthesis of well-defined nanostructured/nanoporous silica/polymer hybrids.