The 30-year-old actress was overjoyed after hearing speculation that the former couple could be back together after they were spotted on a week-long trip to Montana.
She told "The B**** Bible" podcast, "Breaking f****** news. Jennifer Lopez and Ben Affleck are back together. They're in Montana. They are on vacation with each other right now."
Lawrence then gushed, "I'm so excited."
Lopez, 51, and Affleck, 48, were engaged in 2002 but called off their nuptials just days before they were set to walk down the aisle and eventually called time on their relationship in 2004.
The "On the Floor" hitmaker recently called off her engagement to ex-fiance Alex Rodriguez before she was spotted with Affleck in Montana.
It was then revealed Lopez is very "happy" spending time with Affleck and had a "great" time in Montana.
A source said, "She had a great time with Ben. She is happy with him and enjoys spending time with him."
The former couple - who were pictured in a car together near a resort in Big Sky - are believed to have rekindled their romance and have a "strong connection" with one another which has developed very quickly.
Another source said, "(Jennifer) spent several days with Ben out of town. They have a strong connection. It's all been quick and intense, but Jennifer is happy."
However, Lawrence is not the only one who is happy about their reunion as Affleck's friend Matt Damon "hopes" the rumours are true.
He said, "I just heard you guys. I was sitting here waiting to come on TV. It's the first time I heard about it."
"It's a fascinating story. I hope it's true. I love them both. I hope it's true. That would be awesome."