The deal will include close to $50 million in guaranteed money, according to the report posted on ESPN.com.
The Cardinals have scheduled a press conference for Saturday night, at which time they are expected to announce a deal.
Fitzgerald, 27, signed a four-year, $40 million extension in March 2008 that was meant to alleviate the salary cap crunch his previous contract was causing the team, a situation that led to trade rumors.
He has been one of the premier wide receivers in the NFL since the Cardinals selected him No. 3 overall in the 2004 draft -- a big target at 6-foot-3 and 218 pounds who has caught at least 90 passes in five of his seven seasons with Arizona.
Last year, Fitzgerald had 90 receptions for 1,137 yards and six touchdowns. He caught a career-high 103 balls in 2005 and had a career-best 1,431 yards receiving in 2008. His highest TD total was 13, in 2009.
Fitzgerald, who has missed just four of a possible 112 games, has 613 career receptions for 8,204 yards and 65 touchdowns.