Play video content EXCLUSIVE 3/14/19 TMZ.com

Rosario Dawson's all in on Cory Booker for President in 2020, but she might be a little biased ... because she just confirmed with us ... they're in a serious, loving relationship!!!

The actress was at the Reagan National Airport in D.C. Thursday when our guy quizzed her on what's been widely rumored -- she's the woman Booker referred to last month on the Breakfast Club when he said he was dating someone very special, while adding, "I got a boo."

Play video content The Breakfast Club

It didn't take much prodding before Dawson said it was true and began gushing over her man, calling him an amazing human being and saying their relationship is a wonderful thing.

She continued ... "I am just grateful to be with someone that I respect and love and admire so much," and added several more doting words to describe the presidential hopeful.

Speaking of that ... Rosario says Cory would be an amazing Prez, and she's pushing him with a campaign button.