In this study, we extend the technique of the production of small and nearly-monodisperse liposomes using a formerly demonstrated microfluidic hydrodynamic focusing technique toward the continuous-flow synthesis of poly(ethylene glycol) (PEG)-modified liposomes for use in drug delivery applications. Relationships between microfluidic flow conditions and physicochemical characteristics of the produced PEG-modified lipid vesicles were evaluated and the resultant liposomes were used for in vitro cellular uptake studies using a human colon carcinoma cell line (Caco-2). The technique presented here enables the rapid production of liposomes with multiple benefits over traditional batch methods, such as improved monodispersity and enhanced size adjustability with the elimination of postprocessing steps. The realized ability of the microfluidic device to also create PEGylated liposomes using a combination of both native lipids and functionalized lipids renders the technology pertinent for biomedical applications, which is demonstrated this study as well as in our ongoing in vitro cellular uptake studies. This microfluidic technique may be extended to various biomedical applications, including liposomes used for targeted delivery and imaging probes.