Official shirt sponsor John Holland Sales and back-of-shirt sponsor DBL Logistics have both issued statements expressing their discomfort with Sheffield allowing Evans to train at the club at the request of the Professional Footballers’ Association.
Their opposition comes as pressure mounts on the club, with three patrons resigning and a petition against his return gaining tens of thousands of signatures.
DBL said in a statement that is was a business "built with family values at its core" and "strongly condemns rape and violence of any kind against women".
It continued: "DBL Logistics would end its back-of-shirt sponsorship with Sheffield United if the Club employed a convicted rapist."
But it said it would continue its association with the club so long as Evans was re-employed.
Sheffield has clarified that Evans has not been re-employed, but is training in order to return to a level of fitness that will allow him to seek employment in football.
Evans’ return to Sheffield’s training ground has led to widespread condemnation. Three Sheffield United patrons have already quit in protest – former pop star Dave Berry, businesswoman Lindsay Graham and TV presenter Charlie Webster.
More than 160,000 people have signed a petition opposing Evans’ return.
Evans was jailed for five years in April 2012 for raping a woman in a hotel room. He served two-and-a-half years of a five-year sentence. He has always protested his innocence.