The 32-year-old claimed his fourth Olympic gold and seventh medal in in all - a British record haul of Games medals.
He was the penultimate of 37 riders to take to the course and completed the 44km route in 50:39 to triumph by 42 seconds, with fellow British rider Chris Froome third in 51:47.
World champion Tony Martin of Germany clocked 51:21 to claim silver.
Wiggins won the Tour de France's two long time trials last month and had three Olympic gold medals on the track and six in all in his previous three Games.
He showed no signs of fatigue following Saturday's Road Race and reached the first time check after 7.3km, in 8:27, five seconds behind Martin, but thereafter forged forward and took the lead at the second time check, after 18.4km.
We've done it. To win another Olympic title in another event, it's never, ever going to get any better than that.Bradley Wiggins
Wiggins was 11 seconds faster than the German, going through in 23:14 and enhanced his advantage at the third on course time check, after 29.9km and with 14.1km remaining.
The Briton was 22 seconds quicker than Martin, going through in 34:43, compared to the German's 35:06.
Froome was third fastest in 35:25, with Switzerland's Fabian Cancellara fifth fastest. Froome finished strongly to set the provisional best before Martin and then Wiggins beat him.
Wiggins, who is from London, said: 'It's been an amazing six weeks. This was the plan. I've answered all the questions in the last six weeks.
'We've done it. To win another Olympic title in another event, it's never, ever going to get any better than that. I realised on the podium, I don't think anything's going to top that.'