In this study, to prevent manganese dissolution from an acid treatment during the extraction of lithium ions (Li+), silica (SiO2) was mixed mechanically with lithium manganese oxide (Li1.33Mn1.67O4, LMO) by a high-energy milling technique followed by calcination. The milling process ensured high-level chemical homogeneity of metal oxides. The amorphous SiO2 imparted stability to the LMO spinel structure and reduced the level of Mn dissolution during the extraction of Li+ using an acid. X-ray diffraction and thermogravimetric analysis confirmed that the amorphous SiO2 was well mixed in the framework of LMO. The Li-Si-Mn-O composite was used as an efficient adsorbent for the recovery of Li+ from lithium spiked seawater with an adsorption capacity of 43.23 mg g(-1). The adsorption process fitted the Langmuir isotherm well with a correlation coefficient of 0.9831. The kinetic study showed that the adsorption behavior followed pseudo-second-order kinetics. The adsorbent exhibited excellent selectivity towards Li+, even in the presence of competitive cations with a higher concentration than Li+.