Austin caught 81 passes for 1,320 yards and 11 touchdowns last season for the Cowboys.
He was also named to the Pro Bowl for his efforts.
In his first career start last October at Kansas City, Austin recorded 10 catches for a team-record 250 yards and two touchdowns, including a 60-yard game winner in overtime.
"We all are familiar and admire the way Miles has evolved into the player he is today," Dallas VP Stephen Jones said Thursday. "We're also very impressed with the person that he is.
"I've never felt like when we have made this kind of commitment to any individual that we've ever been as prepared or better informed about what he is as a player and as a person. That's a good feeling and made this very comfortable in terms of getting this done."
The Cowboys open their 2010 season Sunday night at Washington.
'Boys agree with Austin
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