The proud papa took to Instagram on Sunday to announce the news, revealing that his lady love gave birth on Monday, Feb 15.
"Life is an ever evolving journey," Valderrama captioned a trio of pics he shared, showing himself and Pacheco cradling their newborn baby girl in their hospital room. "For all those times when our path needs a light.. often angels are sent to show us the way and that we can be more."
"Straight out of heaven we welcome our first daughter... #ItsJustUs3Now 02/15/2021," Valderrama added.
The slideshow also included a close-up photo of their baby girl's precious face, and a heartwarming pic of Pacheco, eyes closed, resting her face on her daughter's and smiling.
The new mom, for her part, shared the news to her Instagram as well, posting the same trio of shots with the same caption, to inform her own friends and followers.
This marks the first child for both Valderrama and Pacheco, who became engaged last January.
The couple first announced the news that they were expecting a baby back in December, with some very stylistic, artsy snapshots posted to Instagram, in which the pair rocked bomber jackets and stood by a classic car with multi-colored smoke in the background.
"I gotta say that I am very happy in my life," the That '70s Show star gushed to ET, just two months before popping the question. "In this very moment I feel like, it's so interesting, you work so far for so long and you feel like all of a sudden you're starting over again."
"In my career, and specifically in my personal life, I am very happy where I am at," he added. "I think that I have grown up to be the man that I am meant to be. I am the most grounded that I've ever been. I'm the most excited and the most energetic about what's ahead of me. I'm ready for the next chapter."