The heart-warming moment Misty Knight asks her mum's partner to adopt her.

Misty Knight has been raised by her mother Nicole, and Ryan Farrell – her mother’s boyfriend – for the majority of her young life.

While not biologically related, Ryan has treated Misty as if she were his own; doing her hair as a little kid, introducing her to alternative music and even taking her to her first rock concert in their home state of Illinois.

And now, after years of being her father even without the title, Misty has asked Ryan to formerly adopt her. In the three-minute-long video, Misty convinces Ryan to read aloud a letter she has penned him. The touching clip, which Misty shared to her personal Facebook page on Sunday, has since gone viral with more than 22 million views.

Captioning the video “I finally asked the man that raised me to adopt me”, Misty told her friends and family she “cannot wait to be a Farrell”.

At first, when asked to read out the letter, Ryan is hesitant, warning Misty and surrounding family members “You’re going to make me cry”, playfully begging to not be recorded.

It didn’t take long for Misty to convince him.

The letter began: “I just want you to know that you are the most amazing man I have ever met.

“You’ve raised me my whole life, from putting my hair in tight Princess Leia buns, forging my signature in fifth grade, jamming out to alternative music, going on Warped Tour and even our first rock concert together, leading up to us laughing at cats wearing leggings.

“I know we are so weird together, but that’s what makes you you, and I cannot imagine not having you in my life. I’m so grateful to be able to call you Dad.

“You’re probably wondering what this letter is for – well, open the damn present already!”

After finding a Batman vs. Superman onesie and some lollies inside – a personal joke between the two – Misty prompts Ryan to find “the main surprise”. The final present is an application for adoption, which leaves Ryan speechless before he launches into a hug with Misty and begins crying.

Through tears he says: “God, I’ve been wanting to do that forever.”

Watch the full video here. 

Misty Nicole Knight | Facebook

Do you know of anyone who has been adopted as an adult?