Over the last decade, the intermolecular recognition of anions in water has been attracting the attention of numerous scientific groups involved in supramolecular chemistry. Most of the literature is on the recognition of anions in one organic phase. The development of systems for the recognition of anions in aqueous media is still a challenging task. In this review, examples of sensors and biosensors based on redox-active monolayers destined for the determination of anions, oligonucleotide sequences and antibodies, as well as kinase inhibitors, in aqueous media will be presented. The very high sensitivity in the picomolar range will be supported by very high values of the interphase receptor–target compound binding constant and reaction coupling efficiency. The mechanism of communication between the redox center and the receptor–target analyte complex, as well as analytical signal generation, will also be discussed.