Brandon Woolveridge, 24, would contact posters on social media who were searching for their missing pets and then falsely told owners that he was in possession of the animals, demanding money for their safe return.
On some occasions, he even threatened to harm or kill the pets if the owners refused.
One victim, who paid Mr Woolveridge £1,000 after he threatened to kill her dog, received a message from the man which read: “Now I can buy a new car.”
In another incident, Mr Woolveridge demanded £1,000 from a victim – claiming that the victim’s dog would be shot if money was not received.
One anonymous victim of Woolveridge’s said: “This male made me feel physically sick.
“During the call, I was shaking and shivering uncontrollably. The fact that he was mocking me made me feel completely humiliated.
“I don’t think I will ever forget the way he made me feel that day.”
Cumbria Police launched Operation Façade, after reports came in from across the country – many of which seemed to be linked to Cumbria.
Mr Woolveridge, from Barrown-in-Furness, Cumbria, was arrested as part of Operation Façade after analysis of phone evidence linked him to several cases of blackmail.
He was convicted on 26 October of nine counts of blackmail and asked for 73 similar offences to be taken into consideration.
The blackmailer has been sentenced to prison for three years and eight months, as well as two months served consecutively for the theft of a young girl’s wheelchair.
Detective Inspector Amanda Sykes, of Cumbria Police’s major incident team, said: “Woolveridge’s victims were already extremely distressed at the loss of their much loved pets, when he cruelly chose to prey on them.
“He then made this ordeal even more traumatic by firstly raising their hopes that their pet would be returned, then frightening them into believing he would harm their pets if he did not get money.
“They would then have their hopes dashed and their money taken when they realised this was all a lie.
“I would like to thank the victims of these dreadful crimes for coming forward and supporting this investigation.
“Although we know they will always suffer from the loss of their pets, we truly hope that seeing Woolveridge appear in court will offer some sense of justice.
“Operation Façade has been a very complex investigation, with over 200 victims to date identified from across the whole of the United Kingdom.
“The investigation is continuing, and we will pursue anyone who has been involved in these blackmail offences or handling the money taken from the victims.
“We would urge people who have lost pets not to send reward money without doing extensive checks that the claim is legitimate – and the pet has been found by that person.
“Checks could involve conducting a video call with the person to see your pet with them – or asking for new photos of your pet; if you do this, please check carefully to make sure any photo is genuine.
“If you have concerns that the person wo has contacted you may be acting fraudulently, then please do not give them any money or personal information and contact the police.”