Soma Sara set up the Everyone's Invited website to highlight victims' stories of sexual abuse
The website "Everyone's Invited" asked victims to post anonymous accounts of abuse they had suffered, and has now received more than 5,000 testimonies.
The Met Police said it has been "reviewing the content" of the site and contacted schools it could identify.
The testimonies include accounts from victims as young as nine.
The Met's lead for rape and sexual offences, Det Supt Mel Laremore, said: "It is deeply concerning to see the number of accounts published on this website, many of which appear to relate to previous or current experiences within educational settings in London and across the country.
"We take all allegations of sexual assault very seriously. We understand the complex and varied reasons why many victim-survivors do not contact law enforcement, but I want to personally reassure anyone who needs our help that we are absolutely here for you."
People who were abused years ago should still come forward and report the incidents, Det Supt Laremore said.
What is Everyone's Invited?
In June 2020, Soma Sara, who is now 22, shared her experience on Instagram of what she calls "rape culture".
Within a week she had received and shared more than 300 anonymous responses of people with stories of "misogyny, harassment, abuse and assault".
The Everyone's Invited website now carries thousands of victims' testimonies, often from schools and universities.
Experiences range from being drugged and raped at parties to explicit images being shared over messaging platforms.
This week, pupils at Highgate School in North London walked out of classes in protest at a perceived "rape culture".
One male ex-pupil told BBC Newsnight that girls were "hounded" for naked selfies at the school. The school's governing body said it was "truly sorry" and had commissioned an external review.
Other private schools in London have reportedly passed allegations of sexual abuse onto police.
Ms Soma, the founder of the site, told the BBC this month: "The testimonies [on the site] expose rape culture and the scale of sexual violence amongst young people in the UK."