The former Fifa executive along with former FAT secretary-general Ong-art Kosinkha were initially sentenced to two years in jail and fined B6,000.
The court later reduced the sentence to one year and four months and fined them B4,000, saying their testimonies were deemed useful.
The suit filed by Pattaya FC president Nathaphon Panyakananukul accused Mr Worawi and Mr Ong-art of making changes to the FAT regulations which were approved by the organisation's members before submitting it to a registrar at the Local Administration Department, which oversees all associations in Thailand, between Aug 23 and Oct 14, 2013.
The new regulations were used at the Oct 17 FAT presidential election won by Mr Worawi who defeated former national team manager Virach Charnpanich. Mr Virach took the case to the Court of Arbitration for Sport (CAS) which ruled in favour of Mr Worawi.
The court yesterday found the pair guilty of document forgery ahead of the 2013 FAT election.
Mr Worawi and Mr Ong-art, now Thai Premier League president, have 30 days to appeal.
Mr Nataphon said he filed the complaint to protect the members removed from the association. The number of members of the association was culled from 184 to 72.
"I did it for the sake of all clubs and to protect our rights," he said.
Mr Worawi’s lawyer Narinpong Jinapuck said the pair were innocent of wrong-doing over the document registration issue and will appeal the ruling.
Mr Worawi has won re-election as president of Thai football three times, despite a slew of scandals and widespread criticism from leading Thai football clubs and fans.
In September, a letter signed by 50,000 fans from across the country demanding his removal was handed to the Prime Minister's Office.
A large number of fans said on several websites that Mr Worawi should resign now or not seek reelection in the next poll.
Mr Worawi had been a Fifa executive member for 18 years until he was voted out in April.
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