Cornerback Patrick Surtain was the defensive star with two interceptions, including a pick in the end zone in the fourth quarter.
The offense didn't have a great day for the Dolphins, but came up with just enough big plays to get the job done.
The biggest offensive play of all came courtesy of James McKnight, who took a reverse in the second quarter and raced 68 yards for a touchdown that turned a 7-3 deficit into a 10-7 lead.
The score came shortly after Tiki Barber had scored on a 2-yard as the Giants capitalized on the Dolphins' only turnover of the day, a Jay Fiedler fumble when he was stripped of the ball by Michael Strahan while back to pass.
The Dolphins' second touchdown was a 1-yard run by Ricky Williams that pretty much sealed the outcome late in the fourth quarter. It was a very satisfying touchdown for Williams, who spiked the ball after getting into the end zone.
Williams was the focus of the Giants defense all day, and he finished with only 39 yards on 22 carries.
Olindo Mare provided the other points, with field goals of 43, 23 and 48 yards.
The Dolphins caught a break on the last play of the first half as Giants kicker Matt Bryant injured his kicking leg while hitting a 43-yard field goal to bring the Giants to within 13-10 at halftime.
Punter Jeff Feagles took over the kicking duties and he missed a chip-shot 29-yard attempt in the third quarter that could have tied the game at 13.
The victory gave the Dolphins a 3-1 record, the same at this time last year, and they maintained their half-game lead over New England and Buffalo in the AFC East.