The heavily tattooed 28-year-old announced the happy news on Instagram.
'👶👶👶I AM GOING TO BE A DADDY👶👶👶 ,' the former reality star wrote.
'It is with uncontainable excitement that my beautiful fiance @katmart.0.0.7 and I would like to announce there is a baby Keller on the way. We could not be more excited to share the news with everyone 👶👶👶'
Last year, Craig announced that he had found love with mother-of-two Katie, 29.
The former navy engineer found fame on Channel Nine's social experiment Married At First Sight.
Paired with Nicole Heir, the short-lived couple split called it quits early on.
This article originally appeared on New Idea.