The 42-year-old actor and Shay Shariatzadeh made their red carpet debut as a couple at AMC Lincoln Square Theater in New York City on Saturday.
"It's a wonderful day for a movie premiere and I got a beautiful date," Cena told ET's Nischelle Turner while on the red carpet, before sharing that he met the engineer while filming his new movie.
"What's truly special about this one is that, no matter what projects I'm involved in in the future, this one will always have a special meaning because I got to film a special project and meet someone special," Cena expressed.
While he wouldn't share any more details about their relationship, he added that "it's going to be a wonderful night" with his lady by his side.
The former WWE star's Playing With Fire co-star, Keegan-Michael Key, went into further detail about how the couple first met. Key told ET that he asked Cena to hang out off set, but he revealed to him that he had a "previous engagement."
When Key pressed him for more information, Cena shared that he met Shariatzadeh at a restaurant after noticing a "group of young ladies."
"There was one woman I was looking at and I couldn't take my eyes off her," Key recalled Cena telling him. "...That's when it started."
Meanwhile, another movie the action star is a part of is Fast & Furious 9, which also includes a cameo by Cardi B.
"She was kind of a surprise," Cena said when asked if he got to work with the rapper. "I was also a surprise, but I think that is what's great about the franchise, their ability to always keep it entertaining for their audiences…[Their audience] spans the globe and it’s a multi-cultural franchise that always prides itself on its diversity."
"Cardi B is a wonderful add. I have no idea what she's doing. My stuff is secretive and everyone else's is as well, but I think it's a wonderful addition to the franchise," he added. "I already know the movie is going to be really phenomenal."
As for his current film, Playing With Fire, Cena plays Jake Carson, one of many rugged firefighters who meet their match when attempting to rescue three rambunctious kids. For the NYC premiere, the cast arrived on a firetruck.
"I really appreciate the New York City Fire Department for rolling out the red carpet. Everybody's been awesome," Cena said of the experience. "I'm so glad that a lot of families are in attendance today. We talked a bunch of times about giving first responders the respect that they have earned, and I think raising awareness about first responders only raises funding, which allows them to do what they can do more efficiently."
"I'm glad we can make a fun movie that people can laugh at and still raise awareness at the same time," he added.