A Texas father utilised social media to fulfil a birthday surprise for his son, and his request has gone viral.

Chad Kleis' oldest son, Hunter, will turn nine years old on March 15, and he wanted to make the autistic child's day incredible.

"Need your help!" Kleis wrote on Facebook last month. "I'm going to try and write this without crying. TOO LATE!!!

"As many of you know, our oldest son Hunter is autistic, and as a result he doesn't have many friends, and he doesn't get invited to birthday parties or sleepovers. His birthday is coming up on March 15^th and he will be turning 9 years old. I would like [to] make it a little extra special...

"I am asking for you to send him a birthday card. (He loves Mickey Mouse, Disney, Pixar Movies, etc), you can send them whenever, and we will hold until his birthday!"

Kleis has hundreds of Facebook friends, but the sweet request was shared by over 10,000 people. He reported that he has received nearly 600 cards and over 50 packages from Australia, Norway, Korea, Ireland, and other countries.

The father of two expressed surprise and humility over the surprising response, and looked forward to sharing the gifts with his nonverbal son

"As his dad, I look at it as my job to protect my son but also to give him the opportunity to have a great birthday like every kid wants to have," he said.

Kleis also runs Hunter's Autism Specials, which provides local discounts to families with autistic children. The dad said he was inspired to found the organisation because of his best friend—his son, Hunter.

Gifts for Hunter can be sent to:

Hunter Kleis
P.O. Box 6506
McKinney, TX 75071