Brown entered the 2005 NFL Draft and was drafted with the 2nd overall pick of the 1st round by the Miami Dolphins. Fellow Auburn University HB Carnell Williams was also in the draft and was selected with the fifth pick in the first round by the Tampa Bay Buccaneers. Brown held out of training camp due to a contract dispute and as a result was not successful running the ball in the first two weeks of the season as he rushed for only 93 yards on 34 carries (2.7 avg.) and no touchdowns. However, he got on track in Week 3 as he rushed for 132 yards on 23 carries (5.7 avg.) and his first career touchdown. He followed this up with a successful Week 4 performance rushing for 97 yards on 17 carries (5.7 avg.). But during Week 5, he had to again share rushing duties with another premier running back, this time Ricky Williams who was returning from a four-game suspension. Brown ended up having only about forty more rushes than Williams during the 2005 season, and was well on pace for a 1,000 yard campaign if it wasn't for them sharing the football. Brown ended up with 207 rushes for 907 yards (4.4 avg.) and 4 touchdowns while having 32 receptions for 232 yards and a touchdown.