The group then force the man to admit he brought condoms with him, before showing them to the camera.
The confrontation, which took place at Bluewater mall in Kent on Sunday, then turned violent when a man from another group started kicking and punching the alleged groomer.
Footage shows the men grappling with the suspect and repeatedly yelling "f**king nonce".
Security guards stepped in to break up the brawl before police arrived at the scene.
Detective Chief Inspector Emma Banks said the 29-year-old man was arrested on suspicion of grooming.
"The arrested man is in custody," she said.
"I strongly discourage people taking the law into their own hands to avoid them and others including individuals who may have been wrongfully identified, being put in any danger.
"Any acts of violence reported will always be fully investigated, and enquiries into this incident are ongoing.
The same group were behind the arrest of two other men in Kent on suspicion of grooming in separate incidents on Friday.