This research investigates the use of Glass Fabric Reinforced Cementitious Matrix (G-FRCM) as a confinement material for slender reinforced concrete (RC) columns with slenderness ratios greater than the slenderness criterion for isolated members. An experimental program was conducted on six slender RC columns, including two control and four G-FRCM-confined specimens. The results demonstrated that the G-FRCM strengthening strategy was highly effective, with the compression resistance of the columns increasing by 22.1% and 55.5% for one and two layers of G-FRCM, respectively, compared to the control samples. The experimental results were used to implement and validate the non-linear behaviour of G-FRCM-confined RC columns, employing the Finite Element Method (FEM) through the ABAQUS software. The results, in terms of compression strength, were consistent compared to the experiments, with a difference of less than 5%. Additionally, a parametric investigation has also been conducted to analyse the influence of the slenderness ratio on the response of confined columns. The findings of this study contribute to the understanding of the use of G-FRCM as a highly effective confinement material for RC columns.