He posed for a photo with South Africa stars Faf de Klerk and Cheslin Kolbe as they held aloft the trophy – which he even touched.
Jarvo, 31, hit the headlines in January when he played sex noises during a live Match of the Day show.
Jarvo -known as Jarvo 69 – watched the final in a hospitality box at Paris’s Stade de France alongside stars including singer Rita Ora and Novak Djokovic – having got in for free by following the tennis ace inside.
After quaffing free champagne and beers, he confidently strolled past security at full-time as South Africa were about to begin celebrating their victory over New Zealand.
Scrum half De Klerk, 32, even recognised Jarvo – saying to him: “Are you that guy?”
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Jarvo – who swigged bottles of champers with the players before being escorted away by cops – told The Sun: “A few of them were coming up to me saying ‘Jarvo’ and shaking my hand.
“I was thinking, mate, you’ve just won the World Cup and you’re more interested in seeing me! I couldn’t believe it.”
Jarvo last year celebrated with Real Madrid players when they won the Champions League and invaded the pitch ahead of Australia’s Cricket World Cup match with India earlier this month.
He added: “I’m going for a hat-trick – the rugby, the cricket and I’ve got another big one coming.”