Cremona prosecutor Roberto Di Martino said that Gattuso and retired Lazio player Cristian Brocchi were allegedly part of a ring that fixed Serie A and other Italian matches at the end of the 2010-11 season.
The duo, who had their homes searched, reportedly face charges of criminal conspiracy and sports fraud.
"Gattuso and Brocchi were connected to the case by the use of phone taps," said Di Martino.
The four people arrested are Salvatore Spadaro, Francesco Bazzani, Cosimo Rinci and Fabio Quadri; each of whom allegedly helped connect fixers to players.
Gattuso, 35, who was in charge at Swiss club Sion until February, was sacked by Serie B club Palermo in September after achieving only two wins and a draw in the first six games of the season.
More than 50 people have been arrested in Italy for match-fixing since mid-2011, with matches under investigation by prosecutors in Cremona, Bari and Naples.
It has resulted in lengthy bans for former Lazio captains Giuseppe Signori and Stefano Mauri, as well as former Atalanta captain Cristiano Doni. Several clubs have also had points deducted.
Prosecutors have detailed an extensive match-fixing ring stretching as far as Singapore and South America that was allegedly in operation for more than 10 years.