The People's Vote campaign is spearheaded by UK lawmakers of various parties, as well as celebrities and business leaders, British media report.
The campaign was launched during a rally in northern London which reportedly saw over a thousand people in attendance, Reuters reports.
"It's a vote to ratify the final deal, which is different to the initial thoughts of people when they bought this product," Liberal Democrat MP Layla Moran, one of the speakers, told reporters afterward.
In the meantime, both the Conservative and Labour parties have ruled out a second referendum. Green Party co-leader Caroline Lucas told attendees of the rally that Brexit was "not inevitable," adding that they will fight in Parliament for a second vote.
"We'll do everything we can in Parliament for a people's vote. This issue is far too important to leave to the politicians."