Contemporary macromolecular chemistry has matured to a pointwhere virtually any polymer structure can be synthesized via combinations of controlled polymerization approaches, postpolymerization modification and efficient ligation strategies. Still, often large hurdles have to be overcome to take the next step in research, that is being able to provide such complex materials reliably on significant scale for use in advanced applications. A solution to this problem is to make use of continuous flow synthesis techniques. Flow reactors are associated with high reproducibility, intrinsically simple reaction scale-up and improved product qualities due to significant reduction of side reactions. Being an established method especially in the pharmaceutical chemistry domain, full potential with regards to macromolecular synthesis did not unfold until very recently.The potential of flow chemistry for preparative macromolecular chemistry will be discussed and explored on the example of thermal and photo-controlled polymerization. Special emphasis will be given to machine-learning strategies for autonomous synthesis. The possibility to build reactor cascades and the advantages of online-monitoring will be highlighted. From there, the synthesis of sequence-defined and sequence-controlled polymer structures is described, based also on microreactor processing. Sequence-controlled macromolecules are associated with unique properties, and their synthesis marks a turning point in macromolecular chemistry, by reaching a level of precision otherwise only known from certain biomacromolecules such as proteins and DNA. Challenges in the synthesis of such materials will be addressed, as well as emerging applications, giving emphasis to monodisperse sequence-defined oligomers that can be accessed from so-called single monomer insertions in combination with advanced chromatography separation techniques