The global push towards clean energy transition has positioned lithium (Li) as a critical mineral enabling decarbonisation. Lithium mining from unconventional reserves such as aqueous brine is becoming crucial as hard rock mining falls short of meeting demand and sustainability targets. However, its recovery from low concentrated brines presents significant challenges. Conventional Li extraction methods based on adsorption, solvent extraction, membrane separation face limitations such as membrane fouling, regeneration issues, and are inefficient in dilute aqueous Li reserves. Recently developed electrochemical intercalation/deintercalation approach has shown promise through highly Li selective electrodes, but previously studied materials (LiMn2O4, LiFePO., LiCoO2) suffer from stability issues, require prior electrode delithiation, and often rely on other critical minerals like Mn and Co. This study investigates tungsten trioxide (WOs) nanoparticles synthesized via flame spray pyrolysis (FSP) as a novel, cost-effective material for lithium extraction from synthetic brine (~1057 ppm). WO3 characterised by powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). confirmed the monoclinic phase with 14 nm of average particle size. Highest Li extraction efficiency (4.07 per cent) was achieved at -1.35 V versus Reversible Hydrogen Electrode (RHE), with inductively coupled plasma - optical emission spectroscopy (ICP-OES) analysis confirming Li recovery 1.2 mg g-1 by FSP WO3, Post reaction X-ray photoelectron spectroscopy (XPS) of the electrode surface revealed partial reduction of tungsten from We* to W5+, supporting the formation of lithiated bronze-like Li.WO3 during intercalation. Further, in situ W L3-edge X-ray absorption near edge structure (XaNES) analysis demonstrated energy shifts toward lower energies at negative potentials (-1.35 V, -0.75 V) versus RHE, confirming W6+ reduction to W5+ Li intercalation, while restoration of original oxidation state at positive potentials (+1.65 V, +1.85 V versus RHE), confirmed Li deintercalation. Further coating of WO3 nanoparticles with reduced graphene oxide (rGO) prevented W dissolution and enhanced charge transfer kinetics. This work establishes FSP WO3 as an efficient material for lithium extraction from dilute aqueous brines while elucidating the underlying intercalation/deintercalation mechanisms. Further, Li selectivity tests showed Brucite Mg(OH)2 as a major precipitate along with Li recovery. Thus, WOs can be used as a potential cathode material used for brines with high Mg/Li ratio such as atacama brine (Chile) offering a scalable and sustainable route for brine-based Li extraction.