A relatively simple way of obtaining polymer vesicles via self-assembly in an aqueous acetone medium is proposed on the basis of biologically active polymer sulfite lignin (lignosulfonate). The size and morphology of polymersomes are controlled according to molecular weight (46.300–60.000 Da), the concentration of lignosulfonate (CLS 0.10–1.28 g/dm3), and the content of acetone (φAc 0.6–4.0 vol %) in the suspension. The resulting polymersomes are characterized by sizes of 200–350 nm, a polydispersity index of 0.25–0.18, and a ζ potential of −26.3 to −51.0 ± 2.2 mV. Air-dried powders of polymersomes isolated from the corresponding suspensions are polydisperse, with sizes ranging from 40 to 300 nm. The morphology of polymersomes is confirmed by electron microscopy data (SEM, TEM, and AFM). In light of the biological activity of lignosulfonate, polymersomes derived from it can potentially be used in such biomedical applications as targeted drug and gene delivery, enzymatic catalysis, and optical imaging in vivo.