Interest in dendrimers is mostly focused on their capability of performing specific functions which, in turn, derive from the possibility of incorporating in predetermined sites of the structure selected functional groups (“pieces of information”). From a topological viewpoint, we can distinguish dendrimers containing electro-active units (a) in the core, (b) in the branches, (c) in the surface, (d) in the core and in the branches, (e) in the core and in the surface, (f) in the branches and in the surface, and (g) in the core, branches and surface. In this review article, we briefly summarize some fundamental concepts concerning the electro-chemical processes occurring in redox-active dendrimers and then we focus on their exploitation in the fields of (i) artificial enzymes and biomimetic models, (ii) molecular batteries, and (iii) sensors with signal amplification. We will discuss some prototypical examples, most of them taken from the work performed in our laboratory, to illustrate the above mentioned functionalities.