High-pressure extraction and ultrasonification extraction techniques were employed to extract bioactive compounds from Berberis koreana. This study aimed to determine the effect of ultrasonification in a high pressure process on the extraction yield, and the anticancer and antioxidant activities of the B. koreana bark extract. The effect of high-pressure extraction time when carried out for 5 and 15 min (HP5 and HP15) was also investigated. The best extraction yield with maximum percentage of phenolic compounds was obtained using high pressure with sonification (HPWS) extraction method. Experimental results indicated that HPWS altered the antioxidant activities, including the scavenging capacity of diphenylpicrylhydrazyl (DPPH) and xanthine oxidase. HP5 and HP15 with conventional extraction have almost similar bioactivity, but showed lower antioxidant and anticancer activities compared to HPWS. The results showed that the application of ultrasonification improved the extraction efficiency for bioactive compounds and, as deduced from chromatographic profiles, it may have allowed the release of new compounds. The scanning electron microscope (SEM) showed evidence of rupturing of the tissue surface treated with HPWS, in contrast to conventional extraction, HP5, and HP15. The HPWS extraction was not only more efficient but also convenient for the recovery and purification of the active compounds of hard plant tissues.