McDuffie's agent, Joel Segal, said the deal was for $20 million, an average of $5 million per year.
McDuffie had two years remaining on a contract that would have paid him $1.3 million this year. Segal threatened a holdout unless an agreement on a new deal was reached before McDuffie was scheduled to report for training camp Friday.
"That was my agent's game plan," said McDuffie. "I was fighting the whole way about that. I'm under contract, and I'm not a guy who wants to miss out on anything. I'm not a guy who likes to holdout, and I'm glad it didn't turn out that way."
McDuffie said he was happy to get a deal done that will keep him a Dolphin.
"I've spent my entire career here and enjoy being a part of this team," he said.
Dolphins coach Jimmy Johnson said locking up McDuffie to a long-term deal was a reward for McDuffie's play and attitude. McDuffie led the NFL last season with 90 receptions.
"O.J. has been the consumate professional," Johnson said. "He's set an example for the team to follow. For the past two years he's been involved in our offseason program almost religiously. He's been a total team player. Some great players aren't professional, but that's not the case with O.J."
McDuffie, a first-round pick of the Dolphins in 1993, hasn't missed a start since the '95 season. In his six-year NFL career, McDuffie has 358 receptions, 4,415 yard and 27 touchdowns.
"I told O.J. that I want to see him retire as a Dolphin," Johnson said. "And this is the way to make that happen."
McDuffie's deal comes on the heels of Dan Marino's extension. The 37-year-old Marino signed a two-year extension in July to clear salary cap space for Miami.
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