We present optical light curves from the Transiting Exoplanet Survey Satellite (TESS) for the archetypical dwarf active galactic nucleus (AGN) in the nearby galaxy NGC 4395 hosting a ∼105 M o˙ supermassive black hole (SMBH). Significant variability is detected on timescales from weeks to hours before reaching the background noise level. The ∼month-long, 30 minute-cadence, high-precision TESS light curve can be well fit by a simple damped random walk (DRW) model, with the damping timescale τ DRW constrained to be 2.3+1.8-0.7 days (1σ). NGC 4395 lies almost exactly on the extrapolation of the τDRW-MBH relation measured for AGNs with BH masses that are more than three orders of magnitude larger. The optical variability periodogram can be well fit by a broken power law with the high-frequency slope (-1.88 ± 0.15) and the characteristic timescale (days) consistent with the DRW model within 1σ. This work demonstrates the power of TESS light curves in identifying low-mass accreting SMBHs with optical variability, and a potential global τ-MBH relation that can be used to estimate SMBH masses with optical variability measurements.