In order to deploy detonation nanodiamonds (NDs) in nanomedicine and drug delivery applications, fundamental understanding of their surface chemistry and drug loading capacity is highly desirable. Herein, bone morphogenetic protein 2 (BMP-2) derived peptide with the sequence KIPKASSVPTELSAISTLYLGGC (molecular weight = 2336 g/mol) have been successfully grafted onto NDs using carbodiimide crosslinker chemistry. Initially, functional surface groups of wet- and dry-oxidized NDs were compared using infrared and mass spectroscopy. Dry-oxidized NDs exhibited the highest amount of carboxylic acid derivatives with a surface loading of 0.113 mmol/g after air annealing at 415 °C for 5 h as determined by mass spectroscopy. Compared to wet-oxidation, the dry-oxidation process showed a 1.4-fold increased amount of carbonyl compounds deduced from infrared and mass spectroscopy. Crosslinking of the carboxylic acid derivatives to the primary amines of BMP-2 derived peptide is feasible in the range of 30–96% total surface coverage of NDs. 1:1 and 5:1 ND-peptide ratios were utilized to study the surface loading of NDs using fluorescence spectroscopy. The chemisorption of BMP-2 derived peptide onto NDs reveals superior surface coverage and results in reproducible amounts of tethered bioactive molecules.