Tejay Fletcher, 35, founder and leading administrator of the iSpoof.cc site, was among scores arrested last November following an 18-month worldwide probe led by London's Metropolitan police.
Last month he pleaded guilty to four charges, including making or supplying an article for use in fraud, encouraging or assisting the commission of an offence, possession of criminal property and transferring criminal property.
But the judge said his "late expression of remorse is regret for being caught rather than empathy for your victims," adding Fletcher "didn't care" about them.
"For all the victims it was a harrowing experience," judge Sally Cahill said as she jailed Fletcher for a total of 13 years and four months.
Fletcher has 18 previous convictions for 36 offenses.
Investigators from Europol, the FBI and other law enforcement agencies nabbed Fletcher and other suspects in Australia, France, Ireland and the Netherlands, and shuttered servers in the Netherlands and Ukraine utilized by an international criminal network.
The online fraud shop offered tools that allowed them to disguise phone calls so they appeared to be from a trusted organization, such as a bank, so they could empty their targets' accounts.
Victims around the world lost at least £100 million ($125 million), including a minimum of £43 million from people in the U.K., London's Southwark Crown Court was told during Fletcher's sentencing.
He bought a £230,000 Lamborghini, two Range Rovers worth £110,000 and an £11,000 Rolex watch after making around £2 million from the site's illegal offerings.
One person lost £3 million, while the 4,785 people who reported being targeted in Britain lost an average of £10,000, according to police.
Fletcher's lawyer, Simon Baker, had told the court his client had no idea of the scale of the eventual fraud when he set up iSpoof in December 2020.
At its peak, the site had 59,000 users, with up to 20 people per minute targeted at one point by callers using technology bought from it.
The Metropolitan police lifted the lid on its biggest ever counter-fraud operation last November, with Commissioner Mark Rowley saying it signaled "a different approach" to cracking down on criminals exploiting technology.