An efficient green ultrasound-assisted procedure for the preparation of five new functionalized 1-alkyl-3-butylimidazolium ionic liquids (ILs) 2 – 6 is described. Their structures were characterized by FT-IR, 1 H NMR, and 13 C NMR spectroscopy and mass spectrometry. The newly synthesized compounds were screened for their antimicrobial and anticancer activities. The former revealed that the ILs exhibited promising activity compared with standard drugs. Moreover, IL 4 was found to be a very promising antiproliferative agent against the human hepatocellular carcinoma (HEPG2), human breast adenocarcinoma (MCF7), and colon carcinoma (HCT116) cell lines and consistently produced low IC 50 values.