Thousands held signs with photos of those kidnapped and the Knesset was lit up in yellow in tribute to them.
Crowds of protestors demanded an immediate hostage deal, chanting: “There is nothing more important, every hostage has to return.”
The protests also included large sections of the crowd chanting against Prime Minister Benjamin Netanyahu.
It reflected the frustration among many of the hostages families over the government’s inability to negotiate a deal that frees the captives.
A speech by Jerusalem Mayor Moshe Lion, was overpowered by protesters shouting “Deal now!
Relatives and supporters of Israeli hostages held in Gaza since the October 7 attacks by Hamas militants hold placards during a demonstration (Photo by Menahem Kahana / AFP via Getty Images)AFP via Getty Images
In London, hundreds of people attended a vigil at St Johns Wood United Synagogue on Sunday. They held photos of the hostages still in captivity and waved Israeli flags during the event.
Prime Minister Rishi Sunak vowed to stand by Israel on the anniversary.
He said: "Today marks six months since the terrorist outrage of October 7 - the most appalling attack in Israel's history, the worst loss of Jewish life since the Second World War.
EJacobs Photography[Missing Credit]
"Six months later, Israeli wounds are still unhealed. Families still mourn and hostages are still held by Hamas."
Sunak added: "We continue to stand by Israel's right to defeat the threat from Hamas terrorists and defend their security.
"But the whole of the UK is shocked by the bloodshed, and appalled by the killing of brave British heroes who were bringing food to those in need."
He called for an immediate humanitarian pause in the fighting, "leading to a long-term sustainable ceasefire."
Rallies in the USA were attended by former hostages and relatives of captives still held in Gaza.
In Washington, 2,000 people attended a rally where former hostage Aviva Seigal, whose husband Keith remains kidnapped, called for a deal to free the 130 people still held in Gaza.
The vigil in front of the Lincoln Memorial In Washington DC, also saw the families of captives Romi Gonen, Or Levy, Sagui Dekel Chen and Omer Neutra, gather to raise awareness of the hostage's plight.
Nuetra’s mother Orna Neutra said: “The need to put together a deal that’s agreed upon by all sides is urgent more than ever.”
US Representative Jamie Raskin said freeing the hostages should be the priority in Gaza.
He said: “We say to all the governments of the world that the freedom, the security and the peace of the hostages and all civilians is the paramount ethical imperative and consideration at this moment.”
Thousands attended a vigil in New York at Dag Hammarskjold Plaza outside the United Nations headquarters.
The father of Itai Chen, whose remains are still being held in Gaza, was among those who gathered.
Speaking at the rally in New York, former prime minister Naftali Bennett said calls for a ceasefire meant nothing without the hostages being released.
He said: “No one call tell us to stop while there is even one hostage there.”
According to reports, Representative Jerry Nadler was booed when he called for an increase in humanitarian aid for those in Gaza.
He told crowds: “We must do more, because we are better than Hamas. We must do more to bring food and assistance to those who are suffering.”
The New York Times reported some people in the crowd shouted “shame” or “bring them home.”
A rally in Toronto was attended by some 2,000 people.
Police worked to keep a small counter protest group away from the vigil.
Two people were arrested according to the Toronto Star.
Other vigils took place in Brussels, Amsterdam, Milan and Paris.
