  We present multiwavelength analyses of an active optical transient AT2021fxu
which shows the appearance of previously absent broad emission lines in a
recent optical spectrum, suggesting a Changing-look (CL) Active Galactic
Nucleus (AGN). During the spectral transition, the brightness in the individual
photometric bands increased up to $\approx$0.6 in the optical bands and up to
$\approx$1.1 magnitudes in the UV bands. The brightening was accompanied by a
blueward shift of the optical spectrum. AT2021fxu shows high X-ray (0.3-10 keV)
flux variability before and after the outburst, with the average X-ray flux
increasing by a factor of $\approx$2 post-outburst. However, the X-ray spectral
shape remains roughly the same, with no significant change in the line-of-sight
column density. AT2021fxu's overall properties are consistent with an
accretion-rate-driven transition from a Type-II to a Type-1 AGN.
