Hamilton is only the second driver to win the title in his second season
Lewis Hamilton was overwhelmed by emotion after capturing the 2008 world championship by a single point at a thrilling season finale in Brazil.
"It's pretty impossible to put into words," said the 23-year-old, who is now the youngest ever F1 champion.
"It's been such a long journey and I'm so speechless. After all the sacrifices we've made I am so thrilled to be able to do this for everyone.
"It was one of the toughest races of my life - if not the toughest."
Hamilton clinched the title when he passed Timo Glock accelerating out of the final corner of the race to snatch the drivers' crown from Felipe Massa, who took the chequered flag ahead of him.
With Massa winning at Interlagos, the Englishman knew he had to finish fifth to claim the title but he had slipped to sixth with one lap to go.
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In one final twist, however, Hamilton overtook Glock's slowing Toyota to clinch the fifth place he needed - and with it the title.
"The team didn't say anything so I thought I was shot," said Hamilton, who became Britain's ninth world champion and the first since Damon Hill in 1996.
"I didn't know where Glock was and Vettel was the guy to beat and I couldn't catch him, so at that point I was going to finish sixth. My heart was in my mouth," said Hamilton.
"When it started to drizzle, I didn't want to take any risks but at the final corner I got past Glock and I couldn't believe it.
BRITAIN'S WORLD CHAMPIONS
Mike Hawthorn (1958)
Graham Hill (1962 and '68)
Jim Clark (1963 and '65)
John Surtees (1964)
Jackie Stewart (1969, '71 and '73)
James Hunt (1976)
Nigel Mansell (1992)
Damon Hill (1996)
Lewis Hamilton (2008)
"I thought 'do I have it, do I have it?' When they told me, I was ecstatic.
"It was absolutely fantastic, an amazing achievement on one of the most troubled days.
"It was such a hard race and I'm ecstatic, very emotional, very thankful for my team and my family and everyone who has supported me.
"I have done enough and we made it. I can forget everything else.
"I need to rest because my heart is on edge. I want to shout out to all my supporters at home - I love them all."
Glock insisted he had not handed the title to Hamilton and explained how his decision not to change tyres as the rain began to fall ultimately cost him fifth place.
"Six laps from the end I asked about the tyre situation and about the weather conditions, and I said every time I'll stay out, 'one more lap, one more lap' and at the end I stayed out for the whole race," the German told BBC Radio 5 Live.
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"That last lap just cost us the chance to be in the top five, and in the end (decided) the world championship."
After a record-breaking rookie season, Hamilton continued to rack up the landmarks with his feat in Brazil.
The Englishman joined Canada's 1997 winner Jacques Villeneuve as the only other driver to claim the championship in just their second season.
At the age of 23 years and 301 days, he succeeded Fernando Alonso, who was 122 days older when he won the title in 2005, as the sport's youngest champion.
He is McLaren's first world champion since Mika Hakkinen in 1999, and joins a club that includes his hero Ayrton Senna and all-time greats Alain Prost and Niki Lauda.
Hamilton, who headed to a Sao Paulo nightclub after the race to celebrate with relatives, team-mates and pop singer girlfriend Nicole Scherzinger, paid tribute to McLaren team boss Ron Dennis, who has mentored him for a decade.
"It's a fairytale story that he gave me that opportunity years ago and he had the foresight to bring me in and groom me to get to this position," Hamilton said.
"I've grabbed it with both hands and I've paid him back. I've paid him back in full so I'm happy with that."
When asked if the title would be the first of many, Hamilton said: "I hope so. I don't know if my heart will be able take that final lap for many more seasons but I'll try to do it in a bit of style maybe."
Massa claimed his sixth Grand Prix win in Brazil but saw the title slip away
Massa struggled to hold back the tears after winning his home Grand Prix but losing the world crown by the smallest of margins.
"I had completely mixed emotions because by the time I had crossed the line, I was still the champion, and then suddenly my engineer was telling me everything on the radio," said the 27-year-old, who was racing in his hometown of Sao Paulo.
"He told me when I was already in turn three that Lewis had passed Glock.
"It was a completely mixed emotion because I was still waiting to hear the confirmation (of the title) and then we didn't have (what we wanted)."
The Ferrari driver had been aiming to become the first Brazilian since the late Ayrton Senna in 1991 to win the drivers' title.
"It was an emotional day for me," said Massa. "The race was perfect, we did everything fantastically in such difficult weather.
"We finished in front and we have to be very proud of that but unfortunately we missed [the championship] by one point.
"But that's racing - we need to be proud of our job, our race, our championship.
"We need to congratulate Lewis because he did a great championship and he scored more points than us, so he deserves to be champion.
"I know how to lose and I know how to win and it is another day of my life from which I am going to learn a lot."
Among those to congratulate Hamilton was former McLaren team-mate and double world champion Fernando Alonso.
The Spaniard has become an arch-rival and outspoken critic of the British-based team after a fraught year with them in 2007, but he went to the McLaren garage two hours after the race.
He shook Hamilton by the hand and said "well done, well done", while the Briton responded: "Thank you mate" and clasped Alonso on the shoulder.
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