Winslow, who hauled down 75 passes for 763 yards and two touchdowns over 16 games for the Tampa Bay Buccaneers last season, is an eight-year NFL veteran.
His agent, Denise White, wrote on her Twitter account, "Congrats to our client @KellenWinslowJr for signing with the Patriots!!!"
Hernandez could be out for as long as six weeks after sustaining a low ankle sprain in Sunday's loss to Arizona.
He has made six grabs for 59 yards and a score so far this the season following a 2011 campaign that saw him haul down 79 passes for 910 yards and seven touchdowns.
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