A novel Schiff base ligand named (E)-2-(((3-hydroxyphenyl)imino)methyl)phenol (H2L) was prepared through condensation of 2-hydroxybenzaldehyde with 3-aminophenol in1:1 ratio. The ligand was characterized using spectroscopic techniques. La(III), Er(III) and Yb(III) complexes derived from H2L ligand have been prepared and characterized by conventional techniques including elemental analyses, infrared, electronic spectra, mass spectra, molar conductivity and thermal analysis. IR spectral data showed that H2L ligand is coordinated to the metal ions in a bi-negative tridentate manner through the azomethine nitrogen and two deprotonated phenolic oxygen atoms. The thermogravimetric analysis data of the complexes displays the existence of hydrated and coordinated water molecules in the complexes. The ligand and its complexes were evaluated for their antibacterial and antifungal activities against different gram positive bacteria (Staphylococcus Aureus and Bacillis subtilis), gram negative bacteria (Salmonella SP., Escherichia Coli and Pseudomonas aeruginosa) and fungi (Aspergillus Fumigates and Candida albicans). The complexes were found to have higher biological activity against bacteria and fungi more than the ligand. The calculated binding energy values of the receptors of the colon cancer (PDB code: 2hq6) and the lung cancer (PDB code: 1x2j) for Schiff base ligand (H2L) were discussed.