World No1 Rutherford produced a fourth-round leap of 8.31m that was enough to clinch gold on an historic day for British athletics.
The Brit finished ahead of world silver medallist Mitchell Watt, who again had to settle for second with a jump of 8.16m, while American Will Claye won bronze with 8.12m – fellow Brit Chris Tomlinson finished sixth with a leap of 8.07m.
Rutherford’s victory marks the first long jump gold for Britain since Lynn Davies in 1964, and the 25-year-old was delighted to complete a journey which started with disappointment at the Beijing Olympics four years ago.
“That is the most amazing feeling in the world,” he said. “Four years ago I had a terrible time and I couldn’t cope very well in the final.
“I knew I was in great shape. I have the most amazing parents you could possibly have and a beautiful girlfriend – I’ve got a pretty good life I’m not going to lie. I can’t tell you how much everybody has worked so hard for me.
“It’s been a long process and to be honest I thought I was going to jump further than that but I don’t care I’m Olympic champion who cares.
“Lynn was an incredible guy and I’m glad I can emulate somebody like that what a night for British athletics – three gold medals out of a possible three.
“It’s incredible I can’t thank everybody at home enough and the crowd were absolutely incredible and I’m so fortunate I got to see my folks in the crowd.
“I don’t think it has sunk in properly yet this is what I’ve dreamt of my entire life. I knew I was going to be a sportsman and then when I picked athletics I knew I wanted to be an Olympic champion and I get to do it in London I don’t know how to describe this – I might wake up in a minute.”
Heptathlete Jessica Ennis claimed Team GB’s first track and field gold moments before Rutherford was crowned champion, and Mo Farah capped a special night for the hosts, with a stunning performance to finish first in the 10,000m.
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