Chambers, an emerging star who is one of the most important parts of the offense, was scheduled to become an unrestricted free agent following the 2004 season.
Instead, he is now under contract through the 2009 season.
Chambers, the Dolphins' second-round pick in 2001, is coming off his most productive season with 64 catches for 963 yards and an AFC-leading 11 touchdown receptions.
The Dolphins' main focus now has to be signing defensive end Adewale Ogunleye, who continues to miss training camp practices as he looks for a big-money long-term deal.
But at least, the Dolphins got one potential headache out of the way.