Farah, who finished in a time of 13 minutes 41.66 seconds, became the seventh man to win both the 5,000m and 10,000m events at the same Olympics.
Dejen Gebremeskel of Ethiopia, this year's fastest man, finished in a time of 13:41.98 in silver with Kenya's Thomas Pkemei Longosiwa in bronze.
Reminiscent of the thunderous roars that filled the Olympic stadium a week ago to pull Farah across the line, the 29-year-old timed his race to perfection once more and delivered a second gold by virtue of another pulsating dash to the finish.
Having been pushed about in the qualifying heats Farah had stayed out of trouble at the back of the pack in the opening laps and resisted the temptation to kick on when the pace picked up at the halfway stage.
With around two laps remaining and showing no signs of the tired legs he had admitted to in qualifying, he made his move to huge roars from the crowd.
Farah picked up the pace and worked hard to see off a number of late challenges before accelerating away from Gebremeskel on the home straight to cross the line.
An elated Farah began his celebrations by doing a few sit-ups before running to greet the crowd.
