Baltimore stuffed Miami's ground attack and negated the Wildcat, but most of all the Ravens harried Pennington into uncharacteristic mistakes. After throwing only seven interceptions during the regular season, he had four during a 22-minute flurry midway through the game.
"We heard all week that they don't turn the ball over," linebacker Ray Lewis said. "But we force turnovers."
With a rookie coach in John Harbaugh and a rookie quarterback in Joe Flacco, wild-card entrant Baltimore (12-5) won for the 10th time in 12 games and will play Saturday at AFC South champion Tennessee.
"We're going to Tennessee," Reed said. "Be there."
The playoff victory was the first for the Ravens since they beat Miami in a first-round game in January 2002. The result put the brakes on this season's remarkable resurgence by the Dolphins (11-6), who won the AFC East after going 1-15 in 2007.
"It has been a special year; that's why it hurts so much," Pennington said. "You want to keep it going and see how far you can take it."
A soft schedule contributed to Miami's turnaround, and there was nothing soft about the Ravens. They forced repeated mistakes by a team that tied an NFL record with only 13 turnovers during the regular season.
Reed had two interceptions, and Jim Leonhard and Fabian Washington made one apiece. Terrell Suggs recovered a fumble by Patrick Cobbs early in the second half at the Miami 19, and four plays later Le'Ron McClain scored on an 8-yard run for a 20-3 lead.
Pennington, playing his first game since being chosen the NFL Comeback Player of the Year, was sacked three times and faced constant pressure.
"It always starts up front," Ravens defensive tackle Trevor Pryce said. "We had some favorable matchups, and we took advantage of them. It's quite simple."
Baltimore's secondary also had Miami overmatched. Pennington, who finished 25-for-38 for 252 yards, said the Ravens made good plays on three of the interceptions, and he regretted throwing only one.
"I just couldn't get them to go my way," Pennington said.
Baltimore allowed just 52 yards rushing, and the Dolphins were limited to 7 yards on two plays from the Wildcat, the innovative formation that helped jump-start their revival.
Field position hurt the Dolphins, who started consecutive possessions at their 20, 6, 20, 20, 20 and 2. But the biggest problem was Baltimore's ball-hawking defense, which led the NFL during the regular season with 26 interceptions, including a league-high nine by Reed.
On the game's pivotal play in the second period, he made an over-the-shoulder catch of Pennington's deep throw after intended receiver Ted Ginn Jr., fell.
"Like playing center field," Reed said.
He headed toward the left sideline, eluded a tackler, reversed his field and sprinted for the right corner of the end zone, scoring after Suggs leveled Pennington at the 5-yard line. That put Baltimore ahead to stay, 10-3.
"It felt like the 200 in track," Reed said. "I don't think I caught my breath until the third quarter."
Flacco was only 9-for-23 for 135 yards, but he committed no turnovers and let the Ravens' defenders control the game.
"They've been doing it all year," the rookie said. "You're sitting on the sidelines, and that's what you expect. You get used to it, and you're asking for it every play. Today, they did it on every play."
Trailing 20-3, the Dolphins tried to rally with a 58-yard drive to the 13 before Reed again intercepted Pennington late in the third quarter.
"No one is surprised at the way Ed Reed plays," Harbaugh said. "He may be the best player in the game."
The Ravens' defensive performance was reminiscent of their 27-13 victory at Miami in October. The Dolphins won nine of 10 after that defeat to earn an improbable playoff berth.
"It hasn't been a good day, but it has been a great year," said Miami owner Wayne Huizenga, who is soon expected to complete his sale of the franchise.
His surprising team finally ran out of surprises. After Ronnie Brown made a one-handed catch for a 2-yard score to make it 20-9, Willis McGahee ran 48 yards to set up the Ravens' final touchdown with 3:53 left.
Baltimore offensive coordinator Cam Cameron's unit didn't have to do much else. But with the result, Cameron won more games at Dolphin Stadium this season than in 2007 as Miami's head coach.
Pennington's four interceptions were a Miami postseason record. ... Flacco completed two passes for 14 yards in the second half. ... Miami went 2-for-11 converting third- and fourth-down situations. ... Baltimore had the ball for less than 27 minutes after leading the NFL in time of possession during the regular season.