The dad, who hasn't been named, explained the mother of his daughter, Faith, left when she was only one-month-old.
"My princess Faith was left with an idiot (me), I hated who I was and what I had," he wrote in the emotive post.
"My parents told me to give her up for adoption but thinking about it, laying there on the sofa alone holding Faith, in my arms she looked me in the eye and grabbed my little finger, barely able to grab the whole thing - 'I'll never let you go' I said."
The dad shared his experience on the Love What Matters Facebook page on 21 January.
In the moving account, the dad explained he has struggled with emotion, friendships and relationships all his life because he has Aspergers syndrome - a form of autism, which affects how a person makes sense of the world, processes information and relates to other people.
But the dad said having his daughter completely changed him.
"Faith was the first and only time I understood what love was. I remember the pregnancy, it was the bump, just a bump on my then girlfriend's body, no more, no less," he wrote.
"'Cold' you're probably thinking, but as the saying goes 'if a tree falls in the forest does it make a sound?' You haven't heard the sound, I didn't see a baby."
The dad then went into detail about the day his daughter was born.
He said during the 14 hours of labour, his senses were "about to explode".
"Screaming, bright hospital lights, nurses speaking what sounded like a foreign language, the smell of the hospital making me sick, there wasn't a detail I couldn't see or missed," he wrote.
"The nurses revealed from underneath the bloodied blanket this baby. Nothing else existed and in what seemed like slow motion this beautiful baby appeared into the world.
"Holding her, all negativity dropped from my body. For one of the very few moments in my life my brain just stopped and I couldn't stop staring... she was mine.
"I made her and from that moment I was suddenly refilled with excitement, love, hope. I WAS A DADDY! I was the proudest man on earth."
The dad explained a month after the birth, he found out his girlfriend had been cheating on him with his best friend.
She said she was leaving him, and leaving their daughter Faith too.
He was encouraged to give Faith up for adoption, but instead he left his job to care for her full-time.
"I was going to do this," he wrote. "Me and Faith against the world.
"And we did and it was hard. The crying was unbearable, my sensory issues were always on edge, my depression worsened.
"I didn't sleep or eat - my sole purpose was to look after this girl. She was depending on me.
"There were times I'd scream after putting her to bed. I'd lock myself in the bathroom and cry fully clothed in the bath tub until I fell asleep."
He explained that having Aspergers usually means he needs time out on a regular basis - something he couldn't do with a newborn baby.
But he used logic - what he called his biggest ally - to his advantage, because babies love routine.
"Over time it got easier and it went from being scary to having a best friend," he wrote.
"I may never be a perfect dad but I try perfectly hard and I love her truly and she loves me... Faith taught me unconditional love.
"This girl will depend on me forever. I got my jobs back. I went to University whilst she was in nursery. Things only got better."
The Facebook post racked up nearly 25,000 likes and was shared 6,000 times in 20 hours.
People commenting on the post praised the dad for not only sharing his story, but sticking with his daughter and becoming an amazing father.
One person wrote: "You sir, are by far a great man and I salute you. What a great job you have done in teaching her [Faith] how to be a man and what a man does."
A woman commented: "*Goosebumps* that right there, that is what it's all about... bravo", to which another woman replied: "Exactly what you said."