Johnson revealed that he participated in the delivery, writing: "I was raised and surrounded by strong, loving women all my life, but after participating in baby Tias delivery, its hard to express the new level of love, respect and admiration I have for @laurenhashianofficial and all mamas and women out there."
He urged other men to "be by your ladys head when shes delivering, being as supportive as you can.. holding hands, holding legs, whatever you can do".
The star added: "If you really want to understand the single most powerful and primal moment life will ever offer – watch your child being born.
"It's a life changer and the respect and admiration you have for a woman, will forever be boundless."
The 45-year-old father, who is an American actor, producer, and semi-retired professional wrestler, wrote: "Your crazy dad has many responsibilities and wears many hats in this big ol world, but being your dad will always be the one Im most proud to wear."
He closed his post saying: "Oh and one more thing.. youre gonna love rollin in daddys pick up truck."
The couple are already parents to two-year-old daughter Jasmine, and Johnson has a child from his former marriage.
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When Jasmine was born, the star also posted a photo of his newborn resting on his chest, writing: "Christmas came early! Within minutes of being born she was laying on daddy's chest."
Johnson is currently starring in Rampage, a film following a team attempting to prevent three animals infected with a dangerous pathogen from destroying Chicago.