The utilization of self-thickening polymer (STP) in conformance control was first investigated. Results show that these STP solutions exhibit an increase in viscosity (even like gel) under certain conditions. The optimized application conditions of this novel STP are as follows: mass concentration, 0.25-0.30 wt %; salinity, 4.0-8.0 wt %; and temperature range, 40-70 degrees C. Environmental scanning images demonstrate that a clear and solid skeleton network structure is formed and the higher the salinity of the brine, the more compact the three-dimensional (3D) network structure. In addition, in-depth flow diversion and water permeability reduction were the main mechanisms of water shut-off treatment for improved oil recovery in oil displacement experiments. Finally, this novel STP with the ability to create a gel-like system is cost-competitive, simpler to apply, and more environmentally friendly than the current polymer cross-linker system. It provides an alternative candidate for conformance control treatments at injection or production wells.