Abstract: Ilmenite, an important raw material for the titanium resources. In the vanadium−titanium magnetite deposits of China’s Panzhihua−Xichang region, ilmenite is often closely associated with chlorite. Currently, single magnetic separation or gravity separation processes struggle to achieve efficient separation of the two minerals. Furthermore, under traditional collector systems such as sodium oleate, the flotation efficiency of ilmenite and chlorite remains low, severely limiting the efficient utilization of titanium resources in this region. Therefore, improving the flotation separation performance of these two minerals is becoming increasingly important. Studies have shown that phenolic hydroxyl groups can adsorb onto the TiO₂ surface. Based on this, this study hypothesized that reagents possessing both a phenolic hydroxyl structure and a certain degree of hydrophobicity was likely to serve as highly selective collectors for ilmenite. Octyl gallate was selected as the subject of this study because its molecular structure contained both a long hydrophobic carbon chain and multiple phenolic hydroxyl groups. Through flotation experiments on single−mineral and artificial mixed ores, this study investigated the effect of octyl gallate (OG) on the flotation behavior of ilmenite and chlorite. Using techniques such as zeta potential measurement, total organic carbon (TOC) analysis, Fourier transform infrared spectroscopy (FTIR), and X−ray photoelectron spectroscopy (XPS), the study investigated the adsorption mechanism of octyl gallate on the surfaces of ilmenite and chlorite, providing new technical insights and theoretical support for the efficient development and utilization of titanium resources in this region. Flotation test results indicate that octyl gallate exhibits excellent selective collection performance for ilmenite. Under a pulp pH of 4 in a single−mineral flotation system, when the octyl gallate dosage is 20 mg/L, the ilmenite recovery rate reaches 93.09%, while the chlorite recovery rate is only 5.79%, achieving efficient separation of the two minerals. Under these conditions, in flotation experiments using artificially mixed ore, the TiO₂ recovery rate in the concentrate reaches 89.95%, while the MgO recovery rate is only 10%; the TiO₂ grade is 43.37%, and the MgO grade is only 1.67%, further confirming the excellent separation performance of octyl gallate. Zeta potential analysis shows that the surface potential of ilmenite changes more significantly after reagent adsorption, indicating stronger adsorption; TOC analysis confirms that the adsorption capacity of ilmenite for octyl gallate is significantly higher than that of chlorite; FTIR test results indicate that octyl gallate undergoes chemical adsorption on the ilmenite surface, whereas there is virtually no adsorption on the chlorite surface; XPS results show that octyl gallate primarily forms stable adsorption bonds by interacting with active Ti sites on the ilmenite surface, while no obvious adsorbate sites are detected on the chlorite surface. In summary, octyl gallate, as a highly selective ilmenite collector, shows great potential for application in the flotation separation of ilmenite and chlorite in the Panzhihua−Xichang region.