Posh have climbed from League Two to the second tier since MacAnthony took charge in 2006 but some fans have criticised the club for a perceived lack of investment this season.
Fry told the Peterborough Evening Telegraph: "Darragh MacAnthony has achieved more in three years than those in charge for the previous 72 years in the club's history achieved between them and one fan moaning about his achievements, his policies and his efforts is one fan too many.
"He has spent £4.5million on players, including £1.1million when Keith Alexander was manager. He has funded the arrival of players like Craig Mackail-Smith, Aaron Mclean and George Boyd who have lit up our stadium for two-and-a-half seasons.
"We haven't just won two promotions, we have won them playing great football while scoring almost 100 goals a season. None of it would have been possible without the chairman.
"The last two sets of accounts have shown £1million losses and the next lot will probably show a £2million loss but he will take it and, unlike many other chairmen, he will not react by selling a player to get his money back."