The actor took to Instagram on Friday to announce that he and his girlfriend, model Alaina Meyer, are expecting their first child.
"We are absolutely over the moon to announce that we will soon be welcoming a little one into this crazy and wonderful world," Galecki, 43, wrote next to a happy close-up of him and Meyer, 21.
"We ask that you please respect our privacy during this celebratory time for us and our families," he continued, adding, "There truly is love out there for all. We hope ours is the ember of yours, as we feel yours is the ember of ours."
Meyer wrote in her own baby announcement on Instagram, "There couldn’t be a better blessing in the world for us and we are over the moon happy."
In December, the former "Roseanne" star shared a black-and-white snap of the pair with their arms sweetly wrapped around one another.
When eagle-eyed fans noticed both were sporting bands on their wedding fingers, they began asking questions in the comments — which led Meyer to deny they'd tied the knot.
She shared a full-color version of the same sweet pic, writing, "#notmarried yet ..." adding a wink emoji.
Congratulations to Johnny and Alaina on their happy baby news!