In this paper, we report on the fluorescence enhancement of Eu coordination complexes in dilute solutions through electrostatic complex micelle formation with an oppositely charged block polyelectrolyte. The coordination complexes alone are oligomeric structures which have many ends where partially coordinated europium is exposed to water. In the presence of oppositely charged polyelectrolytes, the local concentration of the coordination complexes is greatly enhanced, so that they transform into polymeric structures and form electrostatically induced micelles with the block polyelectrolytes. This effectively decreases the number of europium–water coordination bonds, which leads to the enhancement of fluorescence emission. This is the first report that utilizes the concentration responsiveness of the smart coordination polymers to promote the function of the colloids made from them.