We present a novel homogeneous assay for detecting biomolecule interactions in microdroplets by fluorescence polarization (FP) for the first time. The FP assay allows the detection of target biomolecules directly after incubation without removing the detection reagent by separation or washing, making the assay amenable to automation. Using this assay we evaluate protein-protein and drug-DNA interactions. We detect these interactions at concentrations as low as 100nM and 69 pM respectively. This is a proof-of-concept homogeneous labeling assay in droplets for detecting bio-macromolecules.