A novel cotton cultivar, designated DP 449 BG/RR, is disclosed. The invention relates to the seeds of cotton cultivar DP 449 BG/RR, to the plants of cotton DP 449 BG/RR and to methods for producing a cotton plant produced by crossing the cultivar DP 449 BG/RR with itself or another cotton variety. The invention further relates to hybrid cotton seeds and plants produced by crossing the cultivar DP 449 BG/RR with another cotton cultivar.