The magnetic and optical properties of suspension of ferrofluid (FF)-based spherical Fe3O4 magnetic nanoparticles (MNPs) in E7 nematic liquid crystal (NLC) matrix have been investigated experimentally in an isotropic phase. The ferronematic liquid crystal (FNLC) mixture exhibits a uniform molecular interaction under an externally applied magnetic field as low as 2 kOe. While the pure NLC shows the expected positive birefringence behavior, the FNLC mixture shows an improvement in tunability with mainly a negative birefringence behavior. The magnetic measurements of samples, including the magnetization curve, hysteresis loop, and pertinent parameters, are carried out using a vibrating sample magnetometer (VSM). The optical properties of samples within the visible spectral range of 380–900 nm are investigated using spectroscopic ellipsometer (SE) device. The results and analysis of magnetic measurements using VSM device show initial magnetic susceptibility of $2.03\times 10^{-6}$ , $8.25\times 10^{-5}$ , $9.85\times 10^{-4}$ , and $3.38\times 10^{-2}$ for FLC0, FLC1, FLC2, and FLC3 samples, respectively. The analysis of SE data shows ordinary and extraordinary refractive indices $n_{\mathrm {o}}$ and $n_{\mathrm {e}}$ of FNLCs samples from 1.85 to 1.67 and from 1.73 to 1.40, respectively.