[en] We present the first multi-wavelength, high-contrast imaging study confirming the protoplanet embedded in the disk around the Herbig Ae/Be star HD 100546. The object is detected at L′ ($\sim <!--\; ???\; -->3.8\mathrm{\mu <!--\; ??\; -->}\mathrm{m}$) and M′ ($\sim <!--\; ???\; -->4.8\mathrm{\mu <!--\; ??\; -->}\mathrm{m}$), but not at K_s ($\sim <!--\; ???\; -->2.1\mathrm{\mu <!--\; ??\; -->}\mathrm{m}$), and the emission consists of a point source component surrounded by spatially resolved emission. For the point source component we derive apparent magnitudes of $L\mathrm{\prime <!--\; ???\; -->}=13.92\pm <!--\; ??\; -->0.10$ mag, $M\mathrm{\prime <!--\; ???\; -->}=13.33\pm <!--\; ??\; -->0.16$ mag, and $K_s><!--\; >\; -->15.43\pm <!--\; ??\; -->0.06$ mag (3σ limit), and a separation and position angle of ${(0.457\pm <!--\; ??\; -->0.014)}^{\mathrm{\prime <!--\; ???\; -->}\mathrm{\prime <!--\; ???\; -->}}$ and ${(8.4\pm <!--\; ??\; -->1.4)}^{{}^{\circ <!--\; ???\; -->}}$, and ${(0.472\pm <!--\; ??\; -->0.014)}^{\mathrm{\prime <!--\; ???\; -->}\mathrm{\prime <!--\; ???\; -->}}$ and ${(9.2\pm <!--\; ??\; -->1.4)}^{{}^{\circ <!--\; ???\; -->}}$ in L′ and M′, respectively. We demonstrate that the object is co-moving with HD 100546 and can reject any (sub-)stellar fore-/background object. Fitting a single-temperature blackbody to the observed fluxes of the point source component yields an effective temperature of $T_{\mathrm{e}\mathrm{f}\mathrm{f}}={932}_{-<!--\; ???\; -->202}^{+193}$ K and a radius for the emitting area of $R={6.9}_{-<!--\; ???\; -->2.9}^{+2.7}$ $R_{\mathrm{J}\mathrm{u}\mathrm{p}\mathrm{i}\mathrm{t}\mathrm{e}\mathrm{r}}$. The best-fit luminosity is $L=({2.3}_{-<!--\; ???\; -->0.4}^{+0.6})\cdot <!--\; ???\; -->{10}^{-<!--\; ???\; -->4}{L}_{\odot <!--\; ???\; -->}$. We quantitatively compare our findings with predictions from evolutionary and atmospheric models for young, gas giant planets, discuss the possible existence of a warm, circumplanetary disk, and note that the deprojected physical separation from the host star of $(53\pm <!--\; ??\; -->2)$ AU poses a challenge to standard planet formation theories. Considering the suspected existence of an additional planet orbiting at ∼13–14 AU, HD 100546 appears to be an unprecedented laboratory to study the formation of multiple gas giant planets empirically.