Byproducts, co-products, and waste products from other industries are commonly utilized in dairy rations. Coffee is a popular phytochemical-rich commodity in the human food chain and processing of such yields numerous waste products, many of which have the potential to be included in livestock feed. Given the known effect of coffee and coffee residues on the rumen microbiota and metabolizable protein profile, it was hypothesized that inclusion of ground coffee in dairy cattle diets would affect the milk proteome and healthfulness of the milk produced. The objective of this study was to use proteomic analyses to identify and characterize the milk proteome produced by cows fed ground coffee. Ten mid lactation (151 ± 25 DIM) Holstein cows were fed the same base diet ad libitum over a 28-d period in a complete randomized block design, which included 2 supplementation treatments of either (1) 140 g/d (DM basis) of molasses (CON), or (2) 140 g (DM basis) of molasses + 70g/d of ground coffee (GC). Milk samples collected in the last week of the trial were stored for milk proteomic analysis. Milk samples were analyzed by HPLC for analysis of high abundance protein concentrations, including casein isoforms, α-lactalbumin, and β-lactoglobulin. For analysis of the low abundance protein-enriched milk fraction, LC-MS/MS techniques were utilized. All parameters were statistically analyzed using the PROC MIXED of SAS. While no differences in DMI, milk yield, or high abundance milk protein concentrations were observed across treatments, 102 proteins were identified using LC-MS/MS techniques. Abundances of 7 proteins decreased due to dietary treatment, including ENO2 protein, antithrombin-III, glycosylation-dependent cell adhesion molecule, junction plakoglobin, and several immunoglobulin-related proteins. Bioactive proteins including osteopontin, lactoferrin, zinc-2-α-glycoprotein, and lactoperoxidase were not affected by dietary treatment. The changes in the milk proteome are likely due to shifts in post-absorptive metabolism and confirm the potential use of secondary compounds in feeds as a mechanism to alter the milk protein profile.