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Three sets of single domain CoFe2O4 nanoparticles of similar sizes (~ 10 nm) with different values of intrinsic strain have been synthesized at three different growth temperatures (120, 140 and 160 °C). The optical bandgap and saturation magnetization of these similar size magnetic nanoparticles are found to be strongly dependent upon the intrinsic strain present in the nanoparticles. The optical bandgap is found to decrease from 1.84 to 1.67 eV and the saturation magnetization decreases from 66.7 to 35.1 emu/g with increase in the intrinsic strain in the nanoparticles. The presence of intrinsic strain is found to affect the cationic redistribution at the tetrahedral and the octahedral sites of the nanoparticles. The decrease in the optical bandgap of CoFe2O4 nanoparticles with increase in the intrinsic strain is correlated to the presence of more Co2+ at the tetrahedral sites. The change in the saturation magnetization is also correlated to the increase in the population of Co2+ at the tetrahedral sites with increase in the intrinsic strain resulting in an enhanced spin canting at the octahedral sites. [ABSTRACT FROM AUTHOR]