Kotb, 53, shared the same photo, as well as another featuring the pair laughing beside a nearly clean plate.
"Saturday night!" she wrote.
After it was announced on Tuesday that Kotb would serve as Lauer's permanent replacement, she told ET that the transition feels "natural."
"[It] didn't feel like the first day of school. I mean, in a great way," she said of her first day as the permanent co-anchor of Today. "It just felt like it was meant to be like this."
Despite her continuing friendship with Lauer after he was abruptly fired for "inappropriate sexual behavior in the workplace," Kotb said she didn't feel the need to "tap the breaks at all" in accepting the new position. Guthrie added that she couldn't be happier about the decision.
"She stepped up right in and said 'yes.' I think we are just so profoundly lucky to have each other, to be in this moment together," Guthrie told ET. "It feels natural, it feels like this wonderful new thing that also feels familiar and I'm just really happy and excited about the future."
Watch below for more about Kotb's Today promotion, along with Lauer's reaction to the news.