Adam Pearson chatted to the youngster over social networking sites and persuaded her to send him pictures of herself.
The 22-year-old, of Hertford Avenue, South Shields, then threatened to show the photographs to others if she did not continue to do what he wanted.
At Newcastle Crown Court, Pearson pleaded guilty to five charges of inciting a child to engage in sexual activity and one of blackmail.
He was ordered to sign the sex offenders register with immediate effect and was granted bail until he is sentenced next month.
Katherine Dunn, defending, said: “He is fully aware of the likely outcome.
“It was communication over Facebook and Skype and threats to show the photos if she didn’t continue.”
The court heard the offences took place last year.
Judge Sean Morris told Pearson: “Custody is inevitable in this case.”
Words: Karon Kelly, North News and Pictures (NNP).