We report the detection and follow-up of a superstellar flare GWAC181229A with an amplitude of {Delta}R~9.5mag on an M9-type star by SVOM/GWAC and the dedicated follow-up telescopes. The estimated bolometric energy Ebol is (5.56-9.25)x10^34^erg, which makes the event one of the most powerful flares seen on ultracool stars. The magnetic strength is inferred to be 3.6-4.7kG. Thanks to sampling with a cadence of 15s, a new component near the peak time with a very steep decay is detected in the R-band light curve, followed by the two-component flare template given by Davenport+ (2014ApJ...797..122D). An effective temperature of 5340+/-40K is measured by fitting a blackbody shape to the spectrum in the shallower phase during the flare. The filling factors of the flare are estimated to be ~30% and 19% at the peak time and at 54 minutes after the first detection. The detection of this particular event with large amplitude, huge emitted energy, and a new component demonstrates that high-cadence sky monitoring cooperation with fast follow-up observations is very important for understanding the violent magnetic activity.