"You can and will use your own voices to drown out the noise," she added. "Because that's what it is - just noise. But your voices are those of truth and hope. And your voices can and should be much louder."
Meghan, Harry and their baby son Archie now live in Los Angeles, having stepped down from royal duties at the end of March, partly because of intense media intrusion into their lives and critical comments directed toward her.
Meghan's audience on Tuesday included girls and women aged 13 to 22 from 172 countries.
She noted that young women already had begun making positive changes by organising Black Lives Matter protests and advocating for criminal justice reform, mental health resources, and steps to end gun violence.
Going forward, "your gut will tell you what's right and what's wrong, what's fair and unfair," she said.
"The hardest part, and it was the hardest part for me, is to chase your convictions with action."
- Reuters