In 2004, Bailey was traded to the Denver Broncos, who released him in early 2014, following Super Bowl XLVIII. He was signed by the New Orleans Saints shortly afterward, but was released before the start of the regular season. In October 2014, Bailey announced his retirement from the NFL after 15 seasons. He was selected to 12 Pro Bowls in his career, the most ever for a cornerback.
Notable statistics from his Charlton County Indians High School career: Total rushing yards 3573, 58 rushing touchdowns, with 13 100-yard games. He passed for 1211 yards on 74 completions. On defense/special teams he caught 8 interceptions, had 26 KR for 731yds, 22 PR for 318yds. His total offensive yardage was 5855 with 394 points scored. He still holds school records for season rushing yards with 1858, season rushing TDs with 28, season scoring with 180, single game rushing with 417 yards, and tied the record for single game rushing TDs which has stood since 1953 (He is also tied with the same person from 1953 for 3rd with 5).
Bailey received an athletic scholarship to attend the University of Georgia, where he played for the Georgia Bulldogs football team from 1996 to 1998. He was regarded as one of college football's greatest multiple threats (offense, defense and special teams) in his three seasons as a Bulldog. In his final year at Georgia, he registered 52 tackles (four for losses), three interceptions, seven passes defensed, 47 catches for 744 yards (15.8 avg.), five touchdowns, 84 yards rushing on 16 carries, 12 kickoff returns for 261 yards and four punt returns for 49 yards. He averaged 103.5 all-purpose yards per game and logged 957 plays (547 defense, 301 offense and 109 special teams) on the way to earning consensus first-team All-America and first-team All-Southeastern Conference honors and claiming the Bronko Nagurski Trophy as the nation's top defensive player. Against the Virginia Cavaliers in the Peach Bowl, he caught 3 passes for 73 yards, including a 14-yard touchdown, rushed 3 times for 9 yards, returned 5 kickoffs for 104 yards, returned a punt 12 yards, and posted 2 tackles and 1 pass defended at cornerback. In 3 years at Georgia, he played 33 games (24 starts) and recorded 147 total tackles, two fumble recoveries, one forced fumble, eight interceptions and 27 passes defended. He was an All-SEC first-team selection as a sophomore, starting every game at left cornerback and one game at wide receiver.
Bailey was drafted in the first round (seventh overall) of the 1999 NFL Draft by the Redskins. He was the highest drafted player to ever come from his hometown of Folkston, Georgia, an achievement Bailey states was big for his town to increase its interest in football.
On July 24, 1999, Bailey signed a 5-year, $12 million contract including a $2 million signing bonus. Bailey quickly established a reputation as one of the league's best defensive backs. He was a large presence on the Redskins defense and benefited from time spent with Hall of Fame cornerback teammates Deion Sanders and Darrell Green. After the 2003 season, Bailey's contract with the Redskins expired and he threatened to boycott training camp if the club exercised the franchise tag. In a surprising move, the Redskins gave Bailey permission to seek a trade.
Prior to the 2004 season, Bailey was traded to Denver along with a second-round draft pick (who ended up being Tatum Bell) for Clinton Portis.
On September 12, 2004, during the NFL's opening Sunday Night Football game of the season, Bailey intercepted his first pass as a Denver Bronco.
On January 14, 2006, in a divisional playoff game against the New England Patriots, he broke the record for the longest non-scoring play in NFL history at the time. With the Patriots near the goal line, he intercepted a pass from quarterback Tom Brady in the end zone and returned it 100 yards to the New England one-yard line before he was tackled by New England's Benjamin Watson, who is also a former Georgia Bulldog.
In 2009, Bailey did not allow a touchdown in 80 passes thrown his way that year, played on 98% of the snaps and remained one of the best-tackling cornerbacks in the game.
On September 15, 2009, Bailey was chosen for the Broncos 50th Anniversary team by the Denver community. This team was honored during the halftime-show of the Legacy game versus the Patriots on October 11.
In 2010, Bailey matched up against some of the NFL's best wideouts. He held Dwayne Bowe to no catches on 2 targets. The Arizona Cardinals only completed 3 passes on him for 19 yards in a game where he matched up with Larry Fitzgerald. Bailey was selected to play in his record breaking 10th Pro Bowl. No cornerback in NFL history has been to more.
It was announced on February 22, 2011 by the Broncos vice president of football operations, John Elway, that Bailey was re-signed to a 4-year contract 
In 2012, Bailey was named an All-Pro for the 7th time of his career and was selected to the 2013 Pro Bowl. The Pro Bowl selection was his 12th, extending the record he set for trips by a cornerback, and tied the record for most Pro Bowls played, along with Randall McDaniel and Will Shields.
After the Broncos' loss to the Baltimore Ravens in the 2012–13 NFL playoffs, critics blamed Bailey's poor play for two Ravens touchdowns. Ravens receiver Torrey Smith was being covered by Bailey when Smith caught touchdown passes of 59 and 32 yards. The Broncos lost the game 38-35 in double overtime. During the 2013 offseason, Bailey was named the 53rd-best player in the NFL by the league's network, NFL Network.
During the course of the 2013 season, Bailey was limited to a career-low 5 games with a foot injury; however, Bailey returned in time for the playoffs, and held his own when fellow cornerback, Chris Harris, was ruled out for the remainder of the season after a torn ACL. Bailey played in his first Super Bowl at Super Bowl XLVIII in which Bailey had 4 tackles in a 43-8 loss to the Seattle Seahawks.
Bailey is the older brother of former NFL linebackerBoss Bailey, who joined him on the Broncos for one season in 2008 after playing the first five years of his career on the Detroit Lions. They, their oldest brother Ronald, and their cousin Kenny all played at Georgia.