H2TiO3–lithium adsorbent was obtained from the acid-modified precursor Li2TiO3, which was synthesized via the solid-phase reaction between LiOH·H2O and a Ti-rich material. The Ti-rich material containing 88.35% TiO2 was prepared from low-grade titanium slag via an upgrading process primarily involving alkaline roasting and acid leaching-hydrolysis. The parameters for the synthesis and acid treatment of the Li2TiO3 precursor were investigated. It was observed that monoclinic β-Li2TiO3 with good crystallization could be synthesized at 750°C with a Li/Ti molar ratio of 2.5. The adsorbent obtained under the optimized preparation conditions exhibited an excellent lithium adsorption capacity of up to 27.8mg/g in LiOH solution with a Li+ concentration of 2g/L, and the adsorption capacity stabilized at 23 to 24mg/g after several cycles. The adsorbent had better Li+ selectivity in the synthetic salt-lake brine solution. The separation coefficients of Li+ to Na+ and K+ reached 37.5 and 26.9, respectively. •Low-grade titanium slag was upgraded by alkaline roasting and acid leaching-hydrolysis processes.•The obtained Ti-rich material was first used to prepare H2TiO3–lithium adsorbent.•The obtained lithium adsorbent has excellent lithium adsorption performance.