The gathering, held at the Quirino Grandstand, saw supporters bringing posters and streamers that call for Robredo's impeachment or resignation. Some carry slogans "Stop Shaming Duterte."
Some supporters also voiced support for Duterte's planned shift to federalism.
Organizers have said the gathering was not funded by politicians, but with donations from Duterte supporters that reached more than $46,000 or P2.3 million.
The rally is being held despite President Rodrigo Duterte's pronouncement that efforts for Robredo's impeachment must stop.
Despite Duterte's call, several of his supporters—including House Speaker Pantaleon Alvarez—are keen on pursuing impeachment raps against the Vice President.
Threats to impeach Robredo came after the release of her controversial video message, played at a side session organized in line with the UN Commission on Narcotic Drugs annual meeting.
The said recorded message was linked to efforts to oust Duterte, with supporters pointing out it was released a day before the filing of an impeachment complaint against him.
Robredo, who has repeatedly denied involvement in any ouster plot, is currently in South Africa for a series of conferences organized by the Friedrich Neumann Foundation. —Rose-An Jessica Dioquino/ALG, GMA News