Meta's US-based director of content policy Benjamin Good is doing so voluntarily via video link, given he is a foreign citizen.
Various researchers have found that hate surged online in the aftermath of the Bondi shooting in December, when 15 people were killed in an attack on a Jewish festival, prompting the royal commission.
Mr Good will be asked to explain the proliferation of hate speech on Meta's various platforms, a question put to him in April at the Hack the Hate technology conference.
"We remove Holocaust distortion and denial, not because it's false - which it is - but because it's anti-Semitic," he said, as quoted by the Jewish Insider website.
"It is hate speech against Jewish people, so we've drawn a clear line against it."
Meta says it has provided approximately 650 documents and three statements to the royal commission.
Its large online presence reaches millions of Australians each day, including via platforms Facebook, Instagram and Threads, and popular messaging apps WhatsApp and Messenger.
But while it is popular, it is not well-respected.
In June, Meta was named the second most distrusted brand in Australia - behind Optus - in a Roy Morgan survey of businesses.
Facebook Australia policy director Mia Garlick will also appear.
Monday's other witnesses are Tiat Oon Ooi from the streamer Kick and Tal-Or Cohen Montemayor from online anti-Semitism tracker Cyberwell.
Australia's general manager for Anthropic, the owner of the large language model Claude, appeared last week.
The commission had previously been told some social media platforms could not identify anti-Semitic posts that used symbols or intentional misspelling to perpetuate anti-Semitism, even with the help of AI.
But Anthropic's Theo Hourmouzis said its chatbot could capture and even intercept such content.
The Sydney hearings are exploring hateful speech online and in traditional media, with public broadcasters ABC and SBS expected to appear later this week.
The fourth hearing block in Melbourne from July 13 will focus on experiences of anti-Semitism at universities, before a fifth block in Sydney from July 20 examines security arrangements for the Jewish community.
3°C