The Philippines will elect a new president on Monday, and voting will also be held for thousands of other positions. More than 67 million Filipinos are eligible to vote, including about 1.7 million who live overseas, in the Middle East and elsewhere.
Robredo is up against several other candidates for the top job, including former professional boxer Manny Pacquiao and Ferdinand Marcos Jr, also known as “Bongbong”, who is currently leading the race.
Marcos Jr is allied to Sara Duterte-Carpio, daughter of the departing president, who is running for vice president.
Robredo, who is 14th and incumbent vice president of the Philippines, announced her bid for presidency in October, and has Senator Kiko Pangilinan as her running mate.
Gray, one of the country's most influential names, announced her support for Robredo and Pangilinan last month with a vlog titled Pinuno: Para sa Bayan.
Robredo is "the only candidate with experience in all three branches of our government: judiciary as a volunteer lawyer, legislative as a congresswoman, and executive as a vice president", Gray said in the YouTube clip, which has had nearly 700,000 views
On Saturday, Gray took to the stage and gave a five-minute address in support of Robredo to an audience of more than 450,000.
"I think all of us here know that VP Leni Robredo is not a leader that comes every so often," the beauty queen, model and singer said. "She is a once-in-a-generation type of bear of hope and change and if you need proof of that statement, look to the people around you.
"Aren’t we as diverse as our nation, all ages, communities, backgrounds and walks of life? See how VP Leni has inspired us to come out of our homes, out of our comfort zones for us to embolden ourselves to raise our voices, to take part in sometimes uncomfortable conversations and polarising environments."
She also said: "We need to remember that the government has the power to change our lives but we have the power to change the government. The one thing that brought us [here] today is not just a name, it is not just a person, a party, or a colour, it is hope, and I am so proud to raise my voice in the pursuit of that very hope alongside each and every one of you."
Gray, who was born in Australia to a Scottish-Australian father and Filipina mother, won Miss Universe in 2018, but her pageant career started well before that, even in childhood when she was crowned Little Miss Philippines in a Sydney contest back in 1999.
Scroll through the gallery below to see Catriona Gray in Dubai.