Herein we report a semisynthetic method of producing membrane-anchored proteins. Ligation of synthetic lipids with designed anchor structures to proteins was performed using native chemical ligation (NCL) of a C-terminal peptide thioester and an N-terminal cysteine lipid. This strategy mimics the natural glycosylphosphatidylinositol (GPI) linkage found in many natural membrane-associated proteins; however, the synthetic method utilizes simple lipid anchors without glycans. Synthetically lipidated recombinant green fluorescent protein (GFP) was shown to be stably anchored to the membrane, and its lateral fluidity was quantitatively characterized by direct fluorescence imaging in supported membranes. Circumventing the steps of purification from native cell membranes, this methodology facilitates the reconstitution of membrane-associated proteins.