Henderson concluded that Peterson did not demonstrate that the process and procedures surrounding his discipline were unfair and inconsistent.
"He was afforded all the protections and rights to which he is entitled," Henderson stated, "and I find no basis to vacate or reduce the discipline."
Henderson also noted that Peterson's public comments "do not reflect remorse or appreciation for the seriousness of his actions."
Regarding the NFLPA's argument that sitting out the majority of the 2014 season should count as time served, Henderson rejected the notion that the Commissioner's Exempt list qualifies as "discipline."
NFL Media Insider Ian Rapoport reports Peterson's next step is to take his case to federal court.
The NFL suspended Peterson on Nov. 18 stemming from a no contest plea on what the league called "an incident of abusive discipline" toward his 4-year-old son. Because the appeal was denied, Peterson will not be considered for reinstatement before April 15, 2015.
If the conditions of the original six-game suspension stand, Peterson would serve the final three games of this season as well as the first three games of the 2015 season. Per Rapoport, though, Peterson will be on the field for the start of next season provided he cooperates with the NFL over the next four months.
Turning 30 in March, Peterson is no lock to return to Minnesota for his ninth NFL season.