Didcot Town skipper Jamie Heapy, who led the club to glory in the FA Vase in 2005, said fan power had help them find the energy to keep going during their victory over AFC Totton.
More than 300 Didcot supporters made the trip to Testwood Park.
"I thought the fans were tremendous,” said Heapy who has been club skipper for six years.
“In extra-time when we were looking a bit tired they drove us on. You just look at them and see how many there were and it gives you a lift.
“I’m absolutely shattered. The boys have been fantastic this season and it's brilliant to get into the Premier Division.
"The FA Vase win will take some beating, but this is very special."
Boss Stuart Peace added: "The boys worked their socks off – both teams did.
"I thought we deserved to win over the two hours. We had a couple of scares in the second half of extra-time, but we dug in.”
Philip John, who scored the winner, added: “This has got to be the highlight for me because I reached the play-offs with Fleet twice and we lost both times, so this makes up for it.”
Chairman John Bailey said: “I am very proud of everyone connected with the club – the management, the players, the committee and the supporters.
“I don’t think we are going to set it (the Premier Division) alight, so we will have to consolidate. It always takes a couple of months to get used to it.
“We will have to see about the budget, but what we can give, we will give. But we will need more sponsors.”
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