Nikki Bella and John Cena. Picture: Screengrab/Ellentube

Nikki Bella treated her fiancé John Cena to a surprise prom on 'The Ellen DeGeneres Show' because he was too "broke" to go to his own one during his school years.

The 34-year-old professional wrestler teamed up with the chat show host to put on the unexpected dance for him after he admitted he couldn't afford to go to the semi-formal event during his school years. 

He said: "I did not [go to prom]. I went to boarding school, and it was a co-ed boarding school so I kinda saw these people all year anyway. 

"I was dead broke and I had the chance to stay on campus and earn some money so I didn't go to prom."

Ellen then revealed Nikki was going to be his date for a surprise prom and the raven-haired beauty revealed herself in a beautiful purple dress. 

Upon seeing Nikki, he said: "I hate surprises but this one I love."

Ellen then gave John a crown to wear to make him Prom King, and the couple enjoyed an awkward slow dance to Lionel Richie hit 'Three Times a Lady'.

Nikki joked: "We can't dance like this on our wedding."

Earlier in the episode, 40-year-old John admitted he felt really anxious about popping the question to his bride-to-be on WrestleMania 33 last year. 

He said: "I was super nervous, but I was definitely ready to ask her and that's a big change of opinion for me. It took me a long time to get to that point, five years."

Nikki - who started dating John in 2012 - admitted afterwards she had an inkling the pro wrestler was going to propose. 

Speaking last year, she said: "You know what, there was a lot of speculation but his mom was sitting front row - first time she's ever been to a live wrestling event in over 16 years.

"I was like, maybe this is for me, oh no, there might be a swerve to his mom, and then it was for me.

"And then I forgot how to breathe and I got really nervous and I said 'yes.' "