The 29-year-old dropped to his knees in prayer to deafening cheers in the Olympic Stadium after crossing the finish line in the 5000m to become Britain's greatest track and field athlete.
It came seven days after Farah set the stadium alight by winning the 10,000m, making him the first British athlete ever to hold both the 5000m and 10,000m Olympic titles.
Somali-born Farah's stunning win put the golden seal on the last full day of the Games and topped another set of wins for Team GB.
Britain's best medal haul for 104 years was boosted even further when Ed McKeever won gold in the 200m kayak sprint and the two-man crew of Liam Heath and Jon Schofield took a kayaking sprint bronze.
Team GB claimed another gold victory last night in the ring when Luke Campbell, 24, from Hull, won the men's 56kg bantamweight final against Ireland's John Joe Nevin.
The young diver Tom Daley claimed a bronze medal in the 10m diving.
The victories took Britain's medal tally to 61 – 28 gold, 15 silver and 19 bronze – putting Team GB overall third in the leader board behind giants America and China – with 42 and 38 gold medals respectively.
Team GB's medal haul has also lifted the country's mood, with an increase in people who say they are satisfied with life, according to a study. A poll of 2000 people, as part of the monthly Which? consumer tracker, shows a significant jump in life satisfaction during the Olympics.
The day also saw the fastest man on Earth, Usain Bolt, scoop his third gold of the Games and break a world record when he sprinted the final leg of the Jamaican 4x100m relay final race.
Farah looked relaxed and confident as he took to the starting line for last night's race. After a slow start the pace picked up and a nail-biting last lap saw Farah battle it out with Ethiopia's Dejen Gebremeskel, who took silver, and Kenyan Thomas Pkemei Longosiwa, who took bronze.
Farah won the race in 13 minutes, 41.66 seconds. He completed the last mile in just four minutes.
After his victory he ran to a group of his supporters at the side of the track before holding up a Union Flag and beamed with delight.
Farah posed for pictures for fans before rushing to greet his wife Tania – due to give birth to twins any day now – and his daughter Rhianna, six.
Immediately after the race, Farah said: "I got great support from the crowd, it means a lot to me. It's just unbelievable. I was not confident going into the race. In the heat I didn't feel so good, I had to say I felt tired."
He said the double victory meant he could give a gold medal to each of the twin daughters his wife is expecting.
He added: "I want to thank everyone who supported me, coaches from previous years. I can't thank everyone enough. I want to thank my wife, carrying our twins. It's been a long journey, grafting and grafting."
Farah said he was not looking to the future and wanted to enjoy the moment. "I am amazed – two gold medals – who would have thought that?"
London 2012 chairman Lord Coe, a two-time Olympic 1500m champion, said: "Mo Farah – a distance running great and arguably the best British runner of all time."
Earlier, kayak medallist McKeever, left, lived up to his nickname – the Usain Bolt of water – when he won the 200m canoe sprint.
The 28-year-old punched the air in joy as a 20,000-strong crowd celebrated Britain's first medal in Olympic canoeing on Dorney Lake.
McKeever got off to a fast start and led from the front from the halfway point, beating Saul Rivero Craviotto, who took silver with Canadian Mark de Jong winning bronze.
After his victory McKeever said he felt "not elation, more relief and so happy I could do it in front of the home crowd, it's brilliant".
Just over an hour later on the water, Britain picked up another medal as the two-man crew of Liam Heath and Jon Schofield took a kayaking sprint bronze.
Today Welshman Fred Evans, will hope to continue his run in the welterweight boxing finals. And Anthony Joshua won his semi-final bout to secure his place in today's super heavyweight final.
Mhairi Spence, who is 26 and from Inverness, will also go for gold in the final event, the modern pentathlon.
Also yesterday, 400m Syrian hurdler Ghfran Almouhamad was disqualified after failing a drugs test. The 23-year-old had competed in the women's 400m hurdles but failed to get past the first round, finishing eighth in the second heat.
The Government guaranteed funding for Olympic sports until the 2016 Games in Rio de Janeiro. Meanwhile, Olympic gold medallists Greg Rutherford and Tirunesh Dibaba will today attempt to use the success of the Games to tackle child malnutrition in poor countries. The GB and Ethiopian medallists are among several sporting stars urging the Prime Minister to "fire the starting gun on the biggest ever push against hunger and malnutrition" when the UK takes presidency of the G8 next year.
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