The Pittsburgh Steelers have signed Antonio Brown to a four-year, $US68 million contract extension that makes him the highest paid wide receiver in the National Football League, NFL.com reported on Tuesday.

The 28-year-old receiver, whose deal includes a $US19 million signing bonus, had one year remaining on his current contract, which was set to pay him $4.71 million in 2017.

The average $17 million per year salary over the duration of the deal is $2 million higher than that of Cincinnati's A.J. Green, who had previously been the league's highest paid wide receiver, and takes Brown through the 2021 season.

A five-time Pro Bowl player, Brown finished this past season second in the NFL in receptions (106), tied for second in touchdown catches (12) and fifth in receiving yards (1,284).

He posted a photo of himself on Twitter during his contract signing with a message: "Steelers for life."