A Texas native, Fox chose Miami after four injury-hampered seasons for the Detroit Lions.
"I'm very comfortable with South Florida," he said. "I consider it a second home. But the main reason was the Miami Dolphins. I'm so excited to be here. Their offensive line presents a great opportunity for me to come in and compete."
The 6-foot-6, 314-pound Fox is expected to contend for playing time at either guard position or right tackle. The Dolphins will likely have new starters at all three spots as they revamp their offensive line, which endured a dismal 2013 season both on and off the field.
The unit became the focus of the team's bullying scandal.
"Every athlete wants to be a starter," Fox said. "There are some openings in this offensive line, and I came here to give it everything I have and earn a starting job."
At a minimum, the Dolphins anticipate Fox will give them some much-needed depth.
"Jason has been a quality player," general manager Dennis Hickey said. "He's a guy who brings passion, commitment to the game and toughness."
Fox made only three starts with the Lions, all last year at right tackle. He played in eight games in 2013 and was slowed by groin and knee injuries. He had a foot injury in 2011 and didn't play all season.
"I started 47 straight games at Miami," Fox said. "I had some bad luck early in my NFL career, but that's over. I feel 100 percent healthy."
Fox was a fourth-round draft pick by the Lions in 2010.
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