The ruling stands as the first time in Philippine history that a chief justice was removed through a quo warranto plea.
She has been accused of failing to pay about two million pesos (£29,500) in taxes as well as falsifying and tampering with court resolutions.
Complainants Eligio Mallari and Dante Jimenez of the Volunteers Against Crime and Corruption (VACC) filed the first the impeachment complaint against of Chief Justice Maria Lourdes Sereno at the House of Representatives.
The president of the Integrated Bar of the Philippines (IBP) Iloilo Chapter expressed surprise at the Supreme Court (SC) decision ousting Chief Justice Maria Lourdes Sereno. Appointed at age 52, she was supposed to stay in the Supreme Court as chief magistrate for 18 years but lasted less than 6 years.
Solicitor General Jose Calida filed a quo warranto petition against Sereno before the Supreme Court.
Sereno began her indefinite leave of absence.
Sereno has been a staunch critic of Duterte and more specifically the drug war.
Minutes after the decision was announced, a smiling Sereno emerged from the Supreme Court building to tell her supporters, who had gathered in their thousands in the street, that the fight was not over.
THE SC said in the dispositive portion of the ruling, which Te read to reporters, it found Sereno "disqualified from and is hereby adjudged guilty of unlawfully holding and exercising the Office of the Chief Justice".
"Respondent Maria Lourdes P.A. Sereno is ordered to show cause within ten days from receipt hereof why she should not be sanctioned for violating the Code of Professional Responsibility and the Code of Judicial Conduct for transgressing the sub judice rule and for casting aspersions and ill motives to the members of the Supreme Court".
TRT World spoke Ana Santos in Manila.
"After having a lapdog Congress and a seriously wounded Senate, we now have a puppet Supreme Court".
The Philippines has on paper an independent judiciary which is meant to be a check and balance on executive power. "Duterte will be a virtual dictator so the institutions should really wake up".
Lacson, in a tweet, said the SC's decision also saved "imbecile" lawyers from the scrutiny of senator-judges should they convene into an impeachment court. "The Supreme Court, a co-equal branch of government, is duty-bound to uphold the Constitution".
On the SALNs issue, 9 justices said Sereno violated the Constitution with her incomplete submissions: Senior Associate Justice Antonio Carpio, associate justices Teresita Leonardo de Castro, Diosdado Peralta, Lucas Bersamin, Francis Jardeleza, Noel Tijam, Samuel Martires, Andres Reyes Jr, and Alexander Gesmundo.
"Nakibot ako. I was thinking all the while nga they will deny the petition", he said.
"The High Court has spoken". Renato Corona was impeached in 2011 for betraying the public trust and committing culpable violation of the Constitution.
Sereno has been insisting that, under the Constitution, she can only be ousted through impeachment proceedings.
Worldwide rights groups and local critics have accused Duterte of drifting toward authoritarianism after declaring martial law in the south amid a major attack by pro-Daesh militants past year.