His plea comes on the eve of the much-awaited referendum on the country's EU membership and with the Remain side set for victory, according to latest polls.
Renzi warns of the UK becoming a "small and isolated" island if it votes to quit in the poll on Thursday.
He says, "Seen from Italy, a vote to leave Europe would not be a disaster, a tragedy or the end of the world for you in the UK. It would be worse, because it would be the wrong choice.
RELATED CONTENT
"It would be a mistake for which you the voters primarily would pay the price. Because who really wants Britain to be small and isolated?
"If there's one thing the British have never done when faced with a challenge that concerns their future, their very identity, it is to make the wrong choice.
"A Britain less great than it is would go against the very logic of those who want an exit. It would swap autonomy for solitude, pride for weakness, and identity for self-harm."
Writing in the Guardian newspaper on Wednesday, he says, "So don't do it for us. We're just happy to be in the union with you. Do it, rather, for yourselves - what you stand for: both the history of a nation that has always looked beyond itself, and a future as a platform for innovation, which we all envy and admire.
"You won't be brought around or frightened into your choice by pleas or insults. As British people, you will always rise to the occasion. You'll never walk alone.
"We Europeans will respect your voice, your choice, your decision. But that choice has never before been to retreat or to move backwards."
Meanwhile, some have argued that China prefers the UK to stay in the EU, partly because it has been a sympathetic advocate for the country's commercial interests.
There are also fears that a Brexit could have implications for the 50,000 Chinese students who currently study at UK universities.
Paul Cheng, a Hong Kong businessman, told China Daily that China sees Britain's role within the EU as useful to its overall relationship with Europe.
"They see Britain as a good influence on other countries in Europe in the way they look at China."
Elsewhere, former Greens MEP Caroline Lucas made a staunch defence of the EU in a major TV debate with supporters from both sides on BBC on Tuesday.
Lucas, now a Westminster MP and former leader of the party, said, "The EU is the biggest peace project we've ever had … Debates and discussion not bullets and bombs."
According to the latest UK polls, 72 per cent of 16 and 17-year-olds (who cannot vote) support Remain, as do 74 per cent of 18-24-year-olds. However, just 38 per cent of over 65s support Britain's EU membership.