Yohann Ramchelawon, 30, used a photo of a teenage boy he grabbed from the internet to create bogus social media profiles before grooming youngsters, West Midlands Police said.
Ramchelawon, who was arrested at an address in Victoria Lane, Huddersfield, on March 6, utilised Instagram, WhatsApp, Skype and Facebook to target girls aged between 12 and 17.
Some of his victims were also coerced into performing sex acts in front of webcams after Mauritius-born Ramchelawon threatened to share the images they had provided with friends and family.
In a statement issued after Ramchelawon was sentenced at Stafford Crown Court, West Midlands Police said officers picked up the inquiry after an IP address used to message a 12-year-old Manchester girl was traced to a house in Walsall.
Hundreds of indecent images were found on his digital devices as officers uncovered victims from Coventry and Walsall in the West Midlands, plus Lanark in Scotland, Liverpool, St Ives, Shoreham-by-sea and East Ham in London.
Further examination of Ramchelawon's computer and phone revealed he had contacted girls living in New Zealand, Brazil, the United Arab Emirates and Russia.
Ramchelawon - who gave his home address as Walls Street, Halifax, when arrested - was convicted of two counts of inciting a 12-year-old girl to engage in sex acts online, eight charges of possessing indecent images of children and two of distributing the images.
Detective Constable Kerry Haywood, from West Midlands Police's public protection unit, said: "He used various aliases including Ryan Smith and 'Santiago', and claimed to be a teenager who was sending messages during school or college lessons.
"He sent poems, would call them 'baby' and tell them he loved them after chatting online for little more than a day.
"However, he quickly steered the chats to intimate subjects and persuaded them to take their clothes off - and he then used these naked images to blackmail them into sending more explicit pictures and videos.
"The enquiry started when a girl from Manchester reported to police that a boy named Ryan was asking for intimate images.
"The investigation soon snowballed and we identified many more victims and online conversations with girls in different countries.
"I'd like to thank that 12-year-old girl for breaking her silence and putting her faith in the police.
"It's helped us put a calculating sex predator behind bars and undoubtedly protected other girls for falling into his trap."