"I decided to go to Rio 2016," she told Reuters on Wednesday.
Isinbayeva, who had set world records winning gold in Beijing and Athens, never looked comfortable in Monday's final of the women's pole vault on a chilly, rainy evening.
"I will compete at the world championships in Moscow in 2013. I will then have a break, I don't know how long, and then I will be back to go to Rio and get my gold medal back," the 30-year-old said.
The world record holder had previously maintained that she would quit the sport after the 2013 world championships in her native Russia.
She said this week, however, that she did not want to retire with a bronze medal so might think about competing in Rio.
"I would like to retire with an gold Olympic medal and Rio is not that far as we can see because everyone says that four years is too long," said the 30-year-old Russian, attending an International Olympic Committee meeting on the Youth Olympics for which she is an international ambassador.
"It depends on what you are going to do during all this four years. I am really sure that I will do everything right and I will be completely ready for the Rio," she said.
Plagued by injury and poor form and after failing to register a height in the 2009 world championships, she decided to take a break from the sport, returning last year after an 11-month absence.
She won the world indoors in March for her first major title since the 2008 Olympics but her build-up for London had been disrupted in May by a torn thigh muscle.
Her decision to continue for Rio 2016 was welcomed by IOC President Jacques Rogge.
"I heard this morning she will continue her career and then Rio 2016 and that would be wonderful," Rogge told reporters.