Adhesion of soft particles with mobile linkers is of importance in colloidal self-assembly, the binding of vesicles, and tissue organization in biology. Here we derive and experimentally test an equilibrium theory that captures the adhesion of DNA-coated emulsion droplets. Notably, we identify a transition from spherical to deformed droplet binding at a characteristic DNA coverage that depends on molecular properties and surface tension. Fitting the data reveals a weak effective binding strength of 3.7±0.3K_{B}T owing to entropic costs of confinement, crowding, and stretching. Our results pave the path to materials design informed by the choice of molecular-scale parameters.