Serena's 6-0, 6-1 triumph was the most one-sided women's final in Olympic history and marked the culmination of a grasscourt campaign that brought the American her fifth Wimbledon crown and now the third gold medal of her career.
The 30-year-old, who has won two doubles gold medals with sister Venus, is just the second woman to win a Golden Slam of all four major titles and singles gold, emulating Steffi Graf, who achieved the feat in 1988.
Serena is also the first woman to complete a Golden Slam in both singles and doubles. And the 14-time Grand Slam champion isn't finished yet.
She could yet leave the All England Club with another gold as she and Venus are through to the women's doubles final against Czech duo Andrea Hlavackova and Lucie Hradecka after beating Russia's Maria Kirilenko and Nadia Petrova 7-5, 6-4 in the semis.
"Oh my gosh, this one is so high up there, being Olympic gold champion, being Golden Slam champion singles and doubles, that's pretty awesome," Serena said.
"I would have been happy whether I would have got a silver or gold because it's such a great achievement to get on that medal stand.
"But obviously I wanted gold. Now Venus and I both have gold singles, so it's pretty cool."
The Bryan brothers, bronze medallists in Beijing four years ago, won gold as well, beating French second seeds Jo-Wilfried Tsonga and Michael Llodra 6-4, 7-6 (7/2).
The Bryans are the world's top ranked men's doubles pair, a position they have held for 297 weeks, and together they have won a record 78 doubles titles including 11 Grand Slams.
They also have an 18-2 record playing for America in the Davis Cup but, after losing in the semi-finals in Beijing and the quarter-finals in Athens in 2004, an Olympic gold was the missing prize.
Now the American duo have the doubles Golden Slam -- all four major doubles titles and Olympic doubles gold -- and Bob Bryan said: "This is the biggest win of our career. There was a sense of urgency. This could be our last Olympics.
"We got the bronze in Beijing which we were proud about, but our whole goal for this year was to upgrade that medal to something a bit more shiny and we did it."
World number one Victoria Azarenka won bronze in the women's singles with a 6-3, 6-4 victory over Russian 14th seed Maria Kirilenko.
It was a first Olympic medal for Belarus's Azarenka, who celebrated by wrapping herself in her country's red and green flag.
The bronze success is just the latest memorable moment in 2012 for Azarenka, who is enjoying the best year of her career after winning the Australian Open in January and reaching the Wimbledon semi-finals.
"It is just like the weight came off my shoulders," Azarenka said. "It was an incredible match."
There was also a bronze medal victory in the men's doubles for French duo Richard Gasquet and Julien Benneteau, who defeated Spain's David Ferrer and Feliciano Lopez 7-6 (7/4), 6-2.