Watkins, who has a hamstring injury, had already been ruled out of Sunday's game against the Tampa Bay Buccaneers. With the IR designation, he's out a minimum of four games and could return no earlier than Oct. 23 against Washington.
The only one of the Packers' top four receivers who has been cleared to play and taken off the injury report is Allen Lazard, who has been limited in practice this week because of the ankle injury that kept him out of the season opener. Lazard returned for last week's game against the Chicago Bears and is the only receiver on the roster to have caught a touchdown this season.
Watkins, 29, has six catches for a team-high 111 yards through the first two games. He caught three passes for 93 yards vs. the Bears.
Watkins also dealt with hamstring issues last season with the Baltimore Ravens, when he had 27 catches for 394 yards and one touchdown to set career lows in all three categories. Watkins has had injuries for much of his career, which began in 2014 when the Buffalo Bills selected him out of Clemson with the No. 4 overall pick in the draft.
ESPN's Rob Demovsky and The Associated Press contributed to this report.