The death of the striker, who had been receiving treatment for a brain tumour, was announced on Wednesday.
Farren was diagnosed with cancer in 2008 but he made a remarkable comeback and reached 114 goals for Derry in 209 appearances, surpassing the previous record set by Liam Coyle.
He went on to join Glenavon but was forced to retire after becoming ill again, prompting an appeal to fund emergency treatment at a specialist clinic in Mexico.
"We offer our sympathies to his family," said Derry chairman Phillip O'Doherty. "He was a superb player and I think the entire football community throughout Ireland would say the same.
"But, most of all, he was a decent human being."
West Brom midfielder James McClean, who won the League of Ireland first division title with Derry in 2010, paid tribute to his former team-mate on Twitter.
"Gutted to hear news of the death of my former team-mate Mark Farren," he wrote. "Great player, even better man, prayers are with his family, RIP buddy."
Flags were flown at half-mast at the Football Association of Ireland headquarters on Wednesday.