Jennifer, 25, stepped out in a stunning black Mugler dress and carrying a glass of wine to the stage.
The Oscar-winning actress told Meyers, 41, that she was set to ask him out 'years ago' while hosting Saturday Night Live.
'I had a really big crush on you,' Jennifer, who hosted the show in January 2013, said while noting that she created the romance in her head 'because I'm delusional.'
Jennifer said she expected Seth to ask her out, but then decided later in the week during a costume fitting to ask him out.
Related story
Seth Meyers' Netflix stand-up special to debut on Nov 5
