Widows Ankie Spitzer and Ilana Romano, representing the families of the Israelis who died in Munich, said the International Olympic Committee had repeatedly rejected their appeals to hold an official commemoration.
Before the London Games which ended last month, senior international figures including US President Barack Obama and Secretary of State Hillary Clinton called for a tribute to the 11 who were killed in a standoff with Palestinian gunmen.
A German policeman was also killed.
"We have a lot to do yet until Rio comes around but I am absolutely confident that in Rio the circle will come to full closure," Spitzer told Reuters after a commemoration ceremony for the 11 men in Tel Aviv.
It was the last of a number of events held across the world to mark 40 years since the athletes, coaches and an official were killed.
Spitzer said that although she and her fellow campaigners had not been able to persuade the IOC to hold the commemoration, their efforts had raised awareness across the world and many more people now knew about their plight.
"In my opinion it was a big victory that so many people around the world remembered and in so many parliaments and in so many corners of the world people stood in a minute of silence," she added.
Israeli Deputy Foreign Minister Danny Ayalon, who initiated an internet petition he said had got over 100,000 signatures for the IOC to take the lead in commemorating the Munich dead, called on the world body to take responsibility.
"I hope that the IOC will have the courage, the leadership, the decency and the most basic human feelings to do the right thing in Rio de Janeiro," he told Reuters.
Israel's Olympic Committee has organised a commemorative event since the Sydney Games in 2000 and IOC president Jacques Rogge has participated since the Athens Olympics in 2004 but an Israeli official said he hoped the IOC would now take charge.
"I hope that even before Rio the IOC will come up with their ideas about how to commemorate (the 11). There are many ways to do it and I hope they will find the proper way," said Efraim Zinger, secretary general of the Olympic Committee of Israel.
Rogge held a surprise tribute in the athletes' village in July, five days before the London Games opening ceremony but the low-key event failed to satisfy the victims' relatives.
In London, hundreds of guests attended the Israeli commemoration event at the Guildhall with Rogge, top British politicians including Prime Minister David Cameron, Israel's sports minister and Germany's foreign minister present.