A man surprised his grandparents with the news he had become a dad by turning up for Christmas with his newborn son after keeping the pregnancy a secret.

In a video uploaded to TikTok, user @Mcshaneamanda filmed the moment the father of her son carried the newborn into the house to meet his grandparents for the first time - and their reaction has racked up more than 20 million views.

As he walks into the dining room, he tells his family "I've brought you something", as his grandfather asks "Where did you get that?" and his grandmother says "Oh my God, is it yours?"

The pair are left stunned as he introduces them to the newest member of the family, leaving his grandma convinced he's winding her up.

After the baby's mum confirms he is the dad, his grandma screams his name and throws her arms around him in joy.

The heartwarming clip quickly went viral and people flooded the comments asking how the pair had kept it as a complete surprise from his family.

 His grandma refused to believe the news at first (Image: TikTok)

Mum Amanda uploaded a series of videos telling the story which happened at Christmas 2018, explaining she had become pregnant after going on a date with her son's dad Zach, but the pair had decided not to continue the relationship.

Zach had told his parents but had kept the news from his grandparents as he was worried it would "break his grandmother's heart" - but Amanda says she couldn't have been happier for him, as you can see in the video above.

She added that Zach remains a big part of their son's life two years later and his mum has been a life-saver when it comes to helping with childcare.

Viewers loved his grandma's sweet reaction, as one commented to say: "The pure joy and love in her is phenomenal."

A second wrote: "Ya'll I gotta see grandma hold him."

And another joked: "She is the best. 'Who are you, the one who came to the wedding?'"