The externally heated diverging channel method facilitates accurate measurement of the laminar burning velocity (LBV) for premixed liquid fuel-air mixtures under elevated temperatures and ambient pressure conditions. In this study, the method is extended to measure the LBV of iso-octane/air mixtures at higher pressures and temperatures. Detailed experimental and kinetic analyses are conducted on iso-octane/air mixtures at pressures ranging from 1 to 4 atm, temperatures between 409 and 681 K, and different mixture conditions (ϕ = 0.7-1.3). It is observed that the LBV of stoichiometric mixtures increases by approximately 288 % and 315 % when the mixture temperature rises from 300 to 600 K at 1 and 4 atm pressures, respectively. At stoichiometric conditions, the LBV decreases by about 35 %, 32 %, and 31 % as pressure increases from 1 to 4 atm at 300, 450, and 600 K temperatures. A linear increase is noted in both the pressure exponent (β) with the temperature ratio and the temperature exponent (α) with the pressure ratio. Based on these results, a revised LBV power-law correlation is proposed to show the relationship between β and α with temperature and pressure ratios, respectively. Overall, the LLNL model provides a better match to the experimental measurements compared to the CRECK model. The detailed sensitivity analysis revealed that the percentage of active radicals (H, OH, and O) consumption is more prominent compared to the generation of these radicals, leading to a reduction in the LBV with an increase in the mixture pressure. Higher pressure facilitated radical stabilization, promoted the formation of more stable species, and shifted the reaction network toward increased recombination and termination pathways.