Yarraka Bayles posted the clip of her son, Quaden, crying after he was targeted at school for his dwarfism.
"This is what bullying does," she says in the video, in which her son also says he wants to end his life.
The clip, viewed over 14 million times, has triggered an outpouring of support and #WeStandWithQuaden messages.
Celebrities including actor Hugh Jackman and basketball player Enes Kanter have spoken out, while parents in other countries have shared video messages from their children.
Jackman told Quaden "you are stronger than you know, mate" and called on everyone to "be kind".
In the confronting six-minute video, posted on Tuesday, Quaden's mother describes the relentless bullying experienced by her son every day. The family, who are Aboriginal Australian, live in Queensland.
"I've just picked my son up from school, witnessed a bullying episode, rang the principal, and I want people to know - parents, educators, teachers - this is the effect that bullying has," Ms Bayle says as her son sobs.
"Every single... day, something happens. Another episode, another bullying, another taunt, another name-calling.
"Can you please educate your children, your families, your friends?"
The words #StopBullying were trending on Friday as people described their own experiences and urged Quaden to "stay strong".
Children in different countries have also posted messages of friendship.
US comedian Brad Williams, who has the same dwarfism condition of Achondroplasia, said he had raised more than $130,000 (£100,000) in less than a day to send the family to Disneyland.
"This isn't just for Quaden, this is for anyone who has been bullied in their lives and told they weren't good enough," he wrote on the fundraising page.
"Let's show Quaden and others, that there is good in the world and they are worthy of it."
Eric Trump, the son of the US president, described the video as "absolutely heartbreaking". Meanwhile basketball star Enes Kanter tweeted "the world is behind you" and invited the family to an NBA game.
Sports teams in Australia have also rallied behind Quaden, with the indigenous rugby league side inviting him to be lead the team at a match this weekend.
