England, who had brushed aside Scotland 31-7 in the quarter-finals before easing past Samoa 21-19 in the semis, looked set to suffer defeat at the hands of Kenya as they trailed 19-12 with the full-time whistle imminent.
However, captain Tom Powell's converted try drew England level to send the match to sudden-death extra-time, where 20-year-old Sam Edgerley scored the match-winning try.
Powell admitted he had never experienced anything like it and heaped praise on Kenya, who under former England sevens coach Mike Friday were playing in only their second final ever after stunning mighty New Zealand in the semis.
Powell told Sky Sports 1: "That was incredible. The atmosphere is incredible, the Kenyan team are incredible. The physical limits were pushed beyond today. It was amazing, and for the boys to come through like that, after the year we had, just shows the determination and how we've pulled together as a team.
"The boys deserve it."
Hosts New Zealand finished third with a 17-7 victory over Samoa to extend their lead at the top of the series standings to 21 points over Kenya, who climbed up to second. England are up to eighth with 37 points after four rounds.
Scotland were beaten 22-7 in the Plate final while Canada upset Fiji 28-19 to win the Bowl final and Wales saw off Tonga 26-21 to claim the Shield final.