It is understood she agreed to meet him at his workplace in Wyoming, near Gosford.
During the encounter on April 8, the man allegedly sexually assaulted the girl.
She left and told her guardian, who then called police.
The man was arrested in Wyoming on Thursday and charged with aggravated sexual assault and indecent assault.
He was refused bail to appear in Gosford Local Court on Friday.
Badoo allows people to post photographs, interests and a description of why they are on the site. Users are “liked” and end up with a score out of 10.
Sex Crimes Squad commander Detective Superintendent Linda Howlett believes young people are drawn to social media and applications often because of the “like” system.
“One of the trends at the moment, unfortunately, is that children like the likes system so they are accepting a lot of people they don’t know as friends and putting suggestive photos out there to attract likes,” she said.
“They believe they are corresponding with someone of the same age but sex offenders are also using those apps.”
A lot of teens were also prepared to put up with suggestive comments from people online or requests for certain photographs in exchange for those likes, she added.
Superintendent Howlett said police were seeing children as young as 10 being targeted.
“You can walk around shopping centres and see children in prams or as young as 10 who will be on devices … so it’s not hard for anyone to work out the security,” she said.
“A lot of parents don’t have an understanding of the privacy settings and are not aware of the dangers out there for young children.
“Have a frank conversation about what they are posting online and who they are socialising with online.