In this paper, an attempt has been made to evolve a structure-magnetic microstructure – magnetic property correlations in sputtered Fe-Co-Al thin films grown at different thicknesses. Fe-Co-Al thin films with various thicknesses viz., 25, 50, 100, 150 and 200 nm were deposited on Si 〈100〉 substrates at room temperature. Structural studies revealed that the films are crystalline in nature with bcc type structure. The crystallinity and average crystallite size deduced from X-ray diffraction studies were found to increase with increase in film thicknesses. Surface microscopy investigations also showed an increase in grain size with film thickness. All the films exhibited a predominant in-plane (IP) magnetic anisotropy. While the saturation magnetization was found to decrease with increase in film thickness, the coercivity exhibited an increasing trend. A maximum saturation magnetization of about 1300 emu/cc has been realized for the 50 nm thick film. Angular dependent magnetization studies indicated anisotropic magnetic behaviour along the plane of the film. Magnetic microscopy studies carried out using Longitudinal magneto-optical Kerr microscopy showed presence of 180° band domain along the easy direction of magnetization for lower thickness films. With subsequent increase in film thickness a combination of ripple and band domains were observed. With further increase in film thickness, presence of only ripple domains has been observed. The deterioration of IP magnetic properties with increase in film thickness was correlated with the magnetic microstructural observations.