Droplet-based microfluidics has emerged as a powerful tool in synthetic biology. For many applications, chemical functionalization of the droplets is a key process. Therefore, a straightforward and broadly applicable approach is developed to functionalize the inner periphery of microfluidic droplets with diverse reactive groups and components. Instead of covalent modification of the droplet-stabilizing surfactants, this method relies on cholesteroltagged DNA that self-assembles at the droplet periphery. The cholesteroltagged DNA serves as an attachment handle for the recruitment of complementary DNA. The complementary DNA can carry diverse functional groups. We exemplify our method by demonstrating the attachment of amine groups, DNA nanostructures, microspheres, a minimal actin cortex, and leukemia cells to the droplet periphery. It is further shown that the DNAmediated attachment to the droplet periphery is temperature-responsive and reversible. It is envisioned that droplet functionalization via DNA handles will help to tailor droplet interfaces for diverse applications-featuring programmable assembly, unique addressability, and stimuli-responsiveness.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201808647. not universally applicable-it depends on the success of the chemical synthesis and can interfere with the stability and the physical properties of the droplets. Moreover, the binding of the functional group to the droplet periphery is irreversible.DNA nanotechnology, [12] on the other hand can attain the programmable assembly of arbitrary nanoscale architectures like DNA-based lattices, [13] nanopores, [14][15][16] or lid-containing boxes. [17,18] DNA has also been used as a scaffold or linker to assemble secondary components including proteins, [19] gold nanoparticles [20] and liposomes. [21] In addition, networks of emulsion droplets [22,23] or colloid-coated droplets [24] have been created using DNA linkers. Yet in all cases, the linkage was based on biotinylated DNA, which requires additional efforts to graft streptavidin onto the droplet surface. Furthermore, it has never been demonstrated that it is possible to functionalize the interior of block-copolymer surfactantstabilized droplets with DNA.Here, we present a broadly applicable method for functionalizing microfluidic droplets utilizing the hydrophobic interaction of cholesterol-tagged DNA with the droplet-stabilizing surfactant. Notably, the interaction of cholesterol with perfluorinated chains has never been described or exploited before. We show that DNA handles can serve as reversible anchoring points for various components including reactive groups, DNA nanostructures, beads, proteins or even cells. The use of off-the-shelf available DNA holds considerable advantages compared to standard methods for droplet functionalization, including: the broad scope of options for site-directed chemical functionalization, the addressability and programmability due to specific base pairin...