Fractures in geological formations, which are commonly encountered during oil and gas exploration, pose significant challenges by facilitating fluid loss and reducing wellbore stability. Polymer gels hold significant promise as lost circulation materials due to their excellent deformability under pressure and self-adaptability. However, conventional gels face certain limitations, such as poor retention of gel-forming suspensions in fractures, low structural strength, and instability at high temperatures. These issues result in low pressure-bearing capacity and, consequently, reduced effectiveness in sealing formation fractures. This study presents the synthesis of a supramolecular polymer gel (SPG) composed of acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic acid (AMPS), divinylbenzene (DVB), polyvinyl alcohol (PVA), TEMPO-oxidized cellulose nanofibers (CNFs), and laponite via in situ radical polymerization. Due to the synergistic effects of hydrogen bonding and electrostatic interactions, the supramolecular polymer gel-forming suspension exhibits high retention capacity in fractures. The as-synthesized gels demonstrate remarkable temperature resistance and high mechanical strength, attributed to covalent bonding, multiple hydrogen bonding, and electrostatic interactions, along with the high aspect ratio and modulus of CNFs and laponite. This study broadens the application scope of CNFs, laponite, and SPGs, offering a novel approach for the efficient development of unconventional oil and gas resources.