Nicaragua had previously refused to sign the 2015 agreement on the grounds that it did not go far enough to combat global warming.
Ortega gave no date for the signing however, only that it would be in the next days or weeks.
“It is time for Nicaragua to sign the Paris Agreement, so in the next days, in the next weeks, we will be signing the Paris Agreement,” Ortega said on the official July 19 website.
The decision stands to leave the United States and Syria as the only countries outside the global climate pact, which set measures to reduce greenhouse gas emissions to prevent temperatures rising by more than two degrees.
US President Donald Trump in June announced the start of a three-year process to pull out of the agreement signed by 195 countries, on the grounds that it put the US at an economic disadvantage.
“Scientists from more developed countries, scientists working at NASA, European scientists, everyone agrees that we must stop the process that is leading to the destruction of the planet,” Ortega said.
In September, Ortega announced during a private meeting with World Bank directors in Managua that his country would join the Paris Agreement, but the news was later removed from the official government website without explanation.