She has since been on trial for her political life at the Constitutional Court in Seoul, which is set to decide in March whether to approve her removal from office - which would trigger new elections - or return her to the Blue House. However, they did not elaborate on the exact reason behind her no show.
Special prosecutors had asked for 30 more days to conclude unfinished business, including a plan to directly question impeached President Park Geun-hye - who is accused of forcing corporate donations among a string of charges. If she is re-instated, the nation will head to the polls in December as scheduled.
The probe, carried out by the special prosecutor's office, was launched last year after 65-year old Park, now stripped of powers, was accused of colluding with a personal friend, Choi Soon-il, in securing donations from the nation's biggest enterprises for foundations that backed Park's policies.
Park, Choi, Lee and Samsung all deny any wrongdoing.
Hwang, who was Park's justice minister before becoming her prime minister, is considered a potential conservative contender for president.
But she has rejected repeated requests from the judges to make herself available for questioning, and has also refused to answer questions from prosecutors probing the scandal.
Some waved banners threatening "civil war" if the impeachment goes through, others hurled personal threats against the judges. If Park is ousted for good, a presidential election must take place within two months of the ouster to choose her successor.
Choi is on trial for coercion and abuse of power.
Prosecutors say President Park allowed her confidante to meddle in state affairs and that they colluded to extort money from companies.
Ms Park was impeached weeks after an old friend of hers, Choi Tae-min, was arrested.
South Korean acting Constitutional Court's Chief Judge Lee Jung-mi, center, attends the final hearing on whether to confirm the impeachment of President Park Geun-hye at the court in Seoul, South Korea, Monday, Feb. 27, 2017.
"We urge the constitutional court to strictly hold her accountable so that people can no longer feel ashamed of the Republic of Korea".