  In the current paradigm, high redshift radio halos are expected to be scarce
due to inverse Compton energy losses and redshift dimming, which cause them to
be intrinsically faint. This low occurrence fraction is predicted by cosmic ray
electron turbulent re-acceleration models. To date, only a handful of radio
halos have been detected at redshift z > 0.8. We report the MeerKAT detection
of a radio halo hosted by a galaxy cluster ACT-CL J0329.2-2330 at z = 1.23,
making it the highest redshift halo detected thus far. Using L-band and
UHF-band observations, we derive a radio halo spectral index of
$\alpha^{1.3GHz}_{0.8GHz}$ = 1.3 $\pm$ 0.4 and a radio power of P$_{1.4GHz}$ =
(4.4 $\pm$ 1.5) $\times$ 10$^{24}$ W Hz$^{-1}$. This result further confirms
that there is rapid magnetic field amplification in galaxy clusters at high
redshift.
