Murray has played in and lost four times in the finals of major championships, but on a day in which rain gave way to sunshine at the most famous stadium in tennis he overwhelmed Roger Federer in the Olympic final.
It was a 6-2, 6-1, 6-4 decision that created pandemonium inside and outside the All England Club. His victory continued a run of enormous British success at their home Olympics.
The gold medal was the second of the day won by British competitors and the 16th of the Games. Britain's all-time gold medal record is 19, established four years ago in Beijing.
"This is the biggest win of my career, that's for sure," Murray said. "I was expecting an incredibly tough match because he's made it so difficult on me. No way did I expect a score like that."
Murray now has a winning record against Federer, whose 17 major championships are the most in history. He has a 9-8 mark in their matches, although this was the first time Murray had defeated Federer in two years. His most recent loss to Federer had come last month in the Wimbledon final.
Federer made 31 unforced errors to 17 for Murray. On nine occasions Federer could have broken Murray's serve by winning the point, but he failed to win any of them.
Murray had a chance for two gold medals Sunday, but he and Laura Robson were defeated later in the day by Victoria Azarenka and Max Mirnyi of Belarus in the finals of the mixed doubles.
The men's singles bronze medal went to Juan Martin del Potro of Argentina, who defeated Serbia's Novak Djokovic in the third-place match 7-5, 6-4.
In the first match of the day on Centre Court, sisters Venus and Serena Williams won their third Olympic doubles gold medal for the United States with a 6-4, 6-4 decision over Andrea Hlavackova and Lucie Hradecka of the Czech Republic.
Serena Williams added the doubles title to the singles gold medal she won 24 hours earlier in a 6-0, 6-1 blasting of Maria Sharapova.