  We report the discovery of the youngest brown dwarf with a disk at 102 pc
from the Sun, WISEA~J120037.79-784508.3 (W1200-7845), via the Disk Detective
citizen science project. We establish that W1200-7845 is located in the
3.7$\substack{+4.6 \\ -1.4}$ Myr-old $\varepsilon$~Cha association. Its
spectral energy distribution (SED) exhibits clear evidence of an infrared (IR)
excess, indicative of the presence of a warm circumstellar disk. Modeling this
warm disk, we find the data are best fit using a power-law description with a
slope $\alpha = -0.94$, which suggests it is a young, Class II type disk. Using
a single blackbody disk fit, we find $T_{eff, disk} = 521 K$ and $L_{IR}/L_{*}
= 0.14$. The near-infrared spectrum of W1200-7845 matches a spectral type of
M6.0$\gamma \pm 0.5$, which corresponds to a low surface gravity object, and
lacks distinctive signatures of strong Pa$\beta$ or Br$\gamma$ accretion. Both
our SED fitting and spectral analysis indicate the source is cool ($T_{eff} =
$2784-2850 K), with a mass of 42-58 $M_{Jup}$, well within the brown dwarf
regime. The proximity of this young brown dwarf disk makes the system an ideal
benchmark for investigating the formation and early evolution of brown dwarfs.
