Scans confirmed a grade one strain for 30-year-old, who has played 224 games for the Magpies and is entering his 13th season at the elite level.
“Unfortunately for Ben scans confirmed a hamstring strain, and he will now go through a rehab program with the aim of being back into full training within 3-4 weeks,” Collingwood director of football Geoff Walsh said.
Johnson, a member of the 2010 premiership side, is one of two players on the Collingwood list to have played 200 games for the Magpies.
He played 16 games in 2011, including each of the club’s three finals, after missing a chunk a football in the middle of the season through injury.
He made his debut in round one of the 2000 season after being drafted from Preston under 18s with the 62nd overall pick in the 1999 draft.
Johnson has twice finished second in the club best-and-fairest (2004, 2006).
Johnson's injury occurred in the same week dual All-Australian Magpie Alan Didak tore his adductor muscle. Didak is scheduled to miss the next month of football after sustaining the injury on Monday.
