The verdict was confirmed by Nigel Mawer, the chairman of the disciplinary committee of the World Professional Billiards and Snooker Association (WPSBA).
Mawer said that Lee, the 38-year-old former world No.5, has been found guilty of match-fixing charges relating to seven matches.
The sanction will be announced at a separate hearing on September 24 and Lee could face a lifetime ban.
Lee was suspended last October and an independent hearing was arranged by Sport Resolutions UK.
In a statement, the WPBSA said: "Between February 2008 and April 2009, Stephen Lee was in contact with three different groups of people all of whom placed bets on the outcomes of his matches or on the outcomes of frames within his matches or on the exact score of his matches. This took place in seven matches over four tournaments . . . The bets were placed by three groups of people. The first were organised by his then sponsor who opened multiple betting accounts with various associates. These accounts were used to place the bets. The second group were coordinated by his then manager who placed almost identical bets. The third was an individual known to Lee who placed the same bets independently of the other two groups. Lee was in contact with the groups in the lead up to the matches in question and afterwards. In one case the person collected the successful bet and placed half of the winnings into Lee's wife's bank account.
"The total amount bet on these matches was in excess of £111,000 leading to winnings of over £97,000 for the persons placing the bets. It is not clear how much Lee benefited from the activity."
This is the biggest case of match-fixing in snooker since the Australian Quinten Hann was suspended for eight years in 2006 after he was caught in a sting by reporters in which agreed to lose a game at the China Open in return for money.
THE WSPBA STATEMENT on stephen lee
On 2nd October 2012, after a two year police and Gambling Commission enquiry, the Crown Prosecution Service decided not to proceed with a case against Lee and others in relation to match fixing.
On 5th October 2012 the Gambling Commission referred the case back to the WPBSA.
As a result of the WPBSA being notified of suspicious betting on his match with John Higgins on 12th October 2012, Jason Ferguson the WPBSA chairman took the decision to suspend Stephen Lee from all competition pending the outcome of the case.
After receipt of some material from the Gambling Commission and further investigation, Nigel Mawer the Chair of the WPBSA Disciplinary Committee, decided that Stephen Lee had a case to answer in relation to the match fixing allegations.
The allegations were serious and related to match fixing or the provision of inside information to enable persons to win money by betting on those matches. The matches in question were three matches in the Malta Cup 2008, two matches at the UK Championship 2008, one at the China Open 2009 and one at the World Championship 2009.
The WPBSA, in accordance with its Disciplinary Rules, asked Sport Resolutions UK to appoint an independent QC to hear the available evidence. Adam Lewis QC was appointed to hear the case.
The case was heard between the 9th and 11th September 2013 in Bristol.
On 16th September 2013 Adam Lewis QC delivered the following decision:
"Stephen Lee is found guilty of "agreeing an arrangement... [and of] ...accepting or receiving or offering to receive... payment or... other... benefit... in connection with influencing the outcome or conduct of" each of the seven matches in breach of Rule 2.9."
A hearing is set for 24th September 2013 to decide on sanction.
The facts are that between February 2008 and April 2009, Stephen Lee was in contact with three different groups of people all of whom placed bets on the outcomes of his matches or on the outcomes of frames within his matches or on the exact score of his matches.
This took place in seven matches over four tournaments. The matches were Lee v Robertson, Lee v Fu and Lee v Doherty in the Malta Cup 2008 where there was betting on the exact score and the match outcomes. Lee v Hendry and Lee v King in the UK Championship 2008 where the betting was on the outcome of the first frame in each match. Lee v Selby in the China Open where there was betting on the match outcome. Lee v Day in the World Championship where there were bets on match outcome and the exact score. In this match there was 'in match' betting on the outcome of the frames in progress.
The bets were placed by three groups of people. The first were organised by his then sponsor who opened multiple betting accounts with various associates. These accounts were used to place the bets. The second group were coordinated by his then manager who placed almost identical bets. The third was an individual known to Lee who placed the same bets independently of the other two groups. Lee was in contact with the groups in the lead up to the matches in question and afterwards. In one case the person collected the successful bet and placed the half of the winnings into Lee's wife's bank account.
The total amount bet on these matches was in excess of £111,000 leading to winnings of over £97,000 for the persons placing the bets.
It is not clear how much Lee benefited from their activity or of his motivation to get involved in match fixing.
WPBSA Chairman Jason Ferguson said: "The WPBSA have a zero tolerance approach to match fixing. We have an extensive network of contacts across the world with the gambling industry and with bodies such as the International Centre for Sport Security and the Gambling Commission. This particular case was extremely difficult and complicated to bring to a hearing. We believe we have established the world's most sophisticated system in dealing with corruption in sport and we will take every step under the WPBSA Rules to deal with those responsible. Today's ruling is a stark warning to competitors in any sport who could become vulnerable in the future. Stephen Lee was the number 5 player in the world and had the opportunity to be part of snooker's great success story. His future participation in the sport is now in real doubt as he will face a significant sanction."
World Snooker chairman Barry Hearn believes the guilty verdict in Stephen Lee's case sounds a warning to any player tempted to engage in match-fixing - "We know everything".
Lee has been found guilty by the World Professional Billiards and Snooker Association of fixing seven matches in 2008 and 2009. His sanction will be announced next Tuesday, but WPBSA chairman Jason Ferguson warned "his future participation in the sport is now in real doubt".
And Hearn welcomed evidence of the sport's zero-tolerance approach to corruption.
He said: "I'm very happy that they've found that snooker is a clean sport, that we can react when somebody breaks our rules. Stephen Lee was world number five but he broke the rules.
"The message is quite clear. Stephen Lee was a very good snooker player, earning a great deal of money, and in today's world of more and more snooker events and more and more opportunities, what he's lost far outweighs the short-term gain that may have been involved at the time.
"That's the message to young players: we will watch every single game, we do employ a great integrity unit, the envy of most sports, we have a great relationship with gambling commissions around the world - we know everything.
"We will find out, we will pursue and they will get found out, and the punishment will follow.
"Without integrity in sport, there is no sport."
Outspoken world number 10 Mark Allen has not always seen eye to eye with Hearn, but agreed with his calls for a strong deterrent.
Allen wrote on Twitter: "It's took (sic) a long time but glad the Stephen Lee case is drawing to a close. Absolutely no place for that in our sport!! Lifetime ban I hope!!"
Three of the matches involved in Lee's case took place at the 2008 Malta Cup, the round-robin format of which creates the possibility of dead rubbers and, arguably, a greater risk of corruption.
However, Lee was also found guilty of fixing frames at the same year's UK Championship and a match against Ryan Day at the 2009 World Championship.
And Hearn said: "I think if you're mindful to go down this road, there are opportunities every time you take part in any competitive match.
"Round robins? Yes, arguably there's more opportunity, but frankly once you've gone down that road you can break rules in any match you choose - one of the cases was in the World Snooker Championship itself."
About the involvement of such a high-profile player - Lee has won five ranking titles stretching back to the 1998 Grand Prix - he added: "I'm disappointed more than shocked.
"We all know the problems in other sports - whether it be cricket, whether it be athletics - it seems to me that there are so many opportunities these days to break rules.
"Our job is to educate younger players to know the rules exist and to make sure that if they break the rules, the punishment should fit the crime. That is the zero tolerance within the sport of snooker."
India cricketer Sreesanth was recently banned for life for spot-fixing at the Indian Premier League, while track and field - and sprinting in particular - has suffered from a recent spate of failed drug tests.