A mixed ligand Cd(II) complex [Cd(IsoPht)(TEA)H2O]·3H2O was synthesized for the first time by using isophthalic acid (H2IsoPht) and tetradentate triethanolamine (TEA) and characterized by X-ray single-crystal diffraction, FT-IR, and thermogravimetric analysis (TGA). This novel complex crystallizes in the triclinic system with P-1 space group and distorted monocapped trigonal prismatic geometry. The Cd(II) has seven coordinates with bidentate IsoPht, a TEA in the tetradentate mode, and an aqua ligand. The fluorescence properties of the Cd(II) complex and TEA ligand were investigated at room temperature. The present Cd(II) complex was also tested for its antimicrobial activity by in vitro agar diffusion method against some Gram-positive and Gram-negative bacteria and a fungus.