Beneby earned his medical degree at University of the West Indies, Jamaica in 1978 and trained as an anaesthesiologist at the University of Sheffield. He returned to the Bahamas and joined the Princess Margaret Hospital as Associate Lecturer in Anaesthesia. He later became head of the Department of Anaesthesia which also runs the hospital’s Intensive Care Unit. In 1989, Beneby invented an anaesthetic mouthguard to protect the upper teeth from injury due to anaesthetic intubation during surgery. Beneby is a founding member of the Commonwealth of The Bahamas Academy of Medical Sciences and contributed to the founding of Physicians Alliance Limited and the Bahamas-based UWI Medical School Research Committee. In 2017, Beneby was diagnosed with cerebral dural arteriovenous fistula but fully recovered after an endovascular embolization procedure and some rehabilitation therapies.