The gang sold cut-price £10-a-month subscriptions, bragging they made money showing games not otherwise available to watch live in the UK because of "blackout" broadcasting rules.
Their operation, described as the biggest so far, received more than £7m from 50,000 subscribers.
The sentencing follows a rare private prosecution by the Premier League.
The fraud prosecution was brought to protect "some of the world's most valuable content", the league's lawyers said.
It followed a lengthy trading-standards investigation led by Hammersmith and Fulham Council.
And the personal details of many of those who paid for Flawless TV are now in the hands of investigators, raising the question of what action might be taken against them.
At Derby Crown Court, the gang's "prime mover", Mark Gould, 36, was sentenced to 11 years in prison.
Four other members were sentenced to between three and more than five years.
One of them, Christopher Felvus, 36, was also found guilty of voyeurism and possessing indecent images of children, discovered on his computer.
Trading-standards investigator Doug Love led a raid on Gould's smart riverside flat in Greenwich, south London.
"I don't think any of us realised how big it was," Mr Love tells BBC News.
"When we went into the spare bedroom, there were 20 or 30 set-top boxes linked together."
The gang took feeds from broadcasters in the UK, Qatar, the US, Australia and Canada and streamed them a few seconds later via the Flawless service.
The operation developed apps offering Premier League matches and other content, which ran on phones and smart TVs.
Users picked what they wanted to watch from a fully-functional on-screen programme guide.
The gang made £7.2m between 2016 and 2021, according to the league.
Gould personally made more than £1.7m.
Direct subscribers paid £10 a month to watch every Premier League game, compared with about £80 a month for legal services from Sky, BT Sport and Amazon Prime.