Treatment fluids comprising gelling agents that comprise crosslinkable polymers and certain biopolymers, and methods of use in subterranean operations, are provided. In one embodiment, the present invention provides a treatment fluid comprising: an aqueous base fluid; a crosslinking agent; and a gelling agent comprising a polymer that is a crosslinkable polymer, and a polymer that is a biopolymer wherein a molecule of the biopolymer (1) consists only of glucose, or (2) has a backbone comprising one or more units that comprise at least (a) one glucose unit and (b) one linear or cyclic pyranose-type monosaccharide unit, wherein (a) and (b) have different molecular structures.