Murray's stellar year showed no sign of stopping as he successfully defended his title, defeating Argentina's Juan Martin del Potro 7-5 4-6 6-2 7-5.
Britain's world No. 2, who beat Roger Federer for gold at London 2012, emerged victorious from an almighty four-hour struggle against a man whose run to the final has made him one of the most popular athletes of these Games.
"I know tonight's one of the hardest matches that I've had to play for a big, big title," Murray told reporters.
"I think the US Open final I played against Novak (Djokovic) when I won my first slam was very hard. But tonight I found really difficult.
"Emotionally it was tough. Physically, it was hard. There were so many ups and downs in the match.
"It was one of the toughest matches that I've played to win a big event, for sure."
Few gave 141st-ranked del Potro a chance of even getting past the first round after being paired with top seed Novak Djokovic.
But the Argentine not only eliminated Serbia's world No.1 but also accounted for 2008 Beijing gold medalist Rafael Nadal in the semifinals too.
He won bronze four years ago but a succession of wrist injuries have hampered what had promised to be an even more successful career.
