John W. Sidgmore (April 9, 1951 – December 11, 2003) was a corporate executive.

He became the Chief Executive Officer of UUNET Technologies in June 1994. UUNET was purchased by MFS, later taken over by WorldCom, which eventually bought MCI. He later became WorldCom's Chief Operations Officer. Sidgmore worked to revive WorldCom after disgraced CEO Bernard Ebbers left. Sidgmore was instrumental in beginning to turn around the failed company, revealing to federal investigators an $11 billion accounting fraud, left over from Ebbers' management of the company.

John Sidgmore died suddenly on December 11, 2003 at the age of 52 from kidney failure. He is survived by his wife Randi, and their son, Michael.