Austin and Bennett joining the Browns may be a sign that the team plans to be without Gordon for the upcoming season. Gordon is facing a season-long suspension after another failed drug test months ago, this time for marijuana, sources told ESPN's "Outside the Lines" last week.
Despite being suspended without pay for two games and losing two additional game checks last season for his earlier violation of the league's drug policy, Gordon led the Browns with 87 receptions and had nine touchdowns. He led the league with 1,646 receiving yards and became the first player with consecutive 200-yard receiving games.
Meanwhile, the Browns released receiver Greg Little on Friday, a league source told ESPN NFL Insider Adam Schefter.
Little caught 41 passes for 465 yards and two touchdowns last season.
Austin, 29, is the biggest addition among the group. He's a two-time Pro Bowler who had 1,000-yard seasons in 2009 and '10, and two years ago had 943 yards.
He immediately becomes a likely starter, with or without Gordon.
Hamstring injuries slowed Austin in 2013, when he caught just 24 passes for 244 yards.
Austin's recent numbers mirror those of Burleson, also signed by the Browns as a free agent. Over the past three seasons, Austin has 133 catches and 13 touchdowns, and Burleson -- who is expected back during training camp after fracturing his left arm in minicamp -- has 139 receptions and six touchdowns.
Bennett was mainly a slot receiver for the Bears, but he has been productive. In six seasons with Chicago, Bennett caught 185 passes for 2,227 yards and 12 touchdowns.
Information from ESPN's T.J. Quinn, Don Van Natta Jr. and The Associated Press was used in this report.