A twisted British woman allegedly disguised herself as a teenage boy to groom dozens of girls online — so she could sexually assault them, according to a disturbing new report.

Gemma Watts, 21, of Enfield, North London, is accused of posing as 16-year-old “Jake Waton” on social media and swapping intimate photos with her teen victims before meeting up with them at multiple places across the country, the BBC reported.

Watts has pleaded guilty to sexual offenses involving four girls — three 15-year-olds and one only 14 — but police believe she may have assaulted as many as 50, according to the report.

In photos on Snapchat and Instagram, Watts tied her hair in a bun and wore a baseball cap, jogging pants and a hoodie as a disguise, London’s Scotland Yard police told the BBC.

She allegedly “liked” the profiles of girls ages 14 to 16, used teen slang, sent flattering messages and shared suggestive photos before traveling to meet with her victims.

Each of the victims — anywhere from 20 to 50 girls — believed they were talking to a teenage boy until police revealed Watts’ true identity, authorities said.

The alleged predator even spent some time disguised as “Jake” with some of her victims’ parents, police charged.

“It’s been life-changing for all of the victims involved,” Detective Constable Phillipa Kenwright told the BBC.

A Hampshire doctor first raised the alarm to authorities in March 2018 after a young patient said she was seeing an older boy, according to the report.

Watts confessed to police four months later that she had been sexually active as “Jake” with the first three victims.

The woman was released under investigation and then busted once again that October when authorities found her on a train with a fourth girl, the BBC reported.

Watts pleaded guilty in November 2019 to one count of assault by penetration, three counts of meeting a child following sexual grooming and three counts of sexual assault, police told the outlet.