The Prime Minister has praised the JC's Secure Our Shuls campaign and announced that it has secured £3 million a year in extra funding for synagogue security.
Speaking at the annual Community Security Trust dinner on Wednesday, David Cameron said: "CST, the Jewish Chronicle and the All-Party Parliamentary Group have all highlighted the risk to synagogues and other potentially vulnerable Jewish community buildings.
"Tonight I can announce a further £3m. That's over £10m of new money for security, this year and every year, for as long as necessary."
The extra funding is part of a new £11.5m annual package for Jewish community security. Private Jewish schools and colleges will receive £7m for guards and other new measures. CST will also receive £1.5m to build a control centre for its operations. The new money is on top of the annual £2m the government already pays for security at Jewish state schools.
The JC's "SOS" campaign sought implementation of the All-Party Parliamentary Inquiry into Antisemitism's recommendation for a fund to cover the cost of enhanced shul security.
In front of a 1,300-strong audience, the largest ever at a CST dinner, Mr Cameron praised the community's "enormous" contribution to Britain, and vowed that his government would give "everything we have got" to protect Jews.
"Over generations we have built something incredible in our country: a multi-ethnic, multi-faith democracy - and we are not going to let anyone destroy it. At a time when once again the Jewish communities of Europe feel vulnerable and when antisemitism is at record levels here in Britain I will not stand by. It is a measure of the health of our democracy and of the vigour of our institutions that the Jewish community feels safe to live and flourish here. It is about the strength of the values that we stand for."
Mr Cameron also pledged his continued support for Israel, which he described as "an extraordinary nation". He said: "I will always stand up for the right of Israel to defend its citizens… with me you will always have a British Prime Minister whose belief in Israel is unbreakable and whose commitment to Israel's security will always be rock solid."
He praised the country's democracy and congratulated Benjamin Netanyahu on his election win.
His remarks were greeted with a standing ovation from the audience, which included cabinet members, the Chief Rabbi and senior diplomats.
CST chairman Gerald Ronson said the extra funding would allow the charity to provide staff and volunteers with extra protection, including bullet-proof vests.
There were more antisemitic incidents in 2014 than any other year on record, but Mr Ronson urged the community not to "run scared from this storm of extremism, terrorism, antisemitism and hatred of Israel".
He attacked those abroad, including Mr Netanyahu, who had called on European Jews to leave following recent attacks.
Mr Ronson added: "I am British, I am Jewish and I am not running anywhere. Neither is CST and neither should you. We stand proud. We organise. We build. We take responsibility for the next generation. That is the Jewish reaction to adversity."
The dinner's appeal video featured JC reporter Rosa Doherty's first-hand account of an antisemitic incident she witnessed on a London bus.