The actor donned his now-famous ensemble to the movie's big L.A. premiere.
Rocking his red, white and blue-themed ensemble, oversized silver helmet-mask and ludicrously large handgun, Cena was totally in character -- apart from his broad smile and friendly demeanor.
The 44-year-old actor was joined by his wife, Shay Shariatzadeh, who walked the red carpet at the Regency Village Theatre in Los Angeles alongside her costumed husband. The two were often seen holding hands and exchanging kisses in front of the cameras.
While on the red carpet, Cena spoke with ET's Lauren Zima, who jokingly asked the actor who she was talking to today -- Cena or Peacemaker.
"Well, this is a very festive occasion as we premiere The Suicide Squad," Cena said. "I ask myself who I am on a daily basis and the answer changes sometimes. And tonight I am dressed up as Christopher Smith, the Peacemaker."
When asked about how his wife felt about Cena rocking the Peacemaker costume out and about -- as he's done quite a lot recently while promoting the new movie -- Cena joked, "Oh those are conversations that we have together, in the privacy of our own home."
As for whether the costume itself has been worn in the privacy of their home, Cena quipped, "I can't confirm or deny that."
Several of Cena's co-stars spoke with ET about the actor's proclivity for rocking the Peacemaker garb, including Nathan Fillion, who laughingly teased, "He hasn't taken it off in weeks."
"That is commitment to a bit," Fillion added. "That is a life of dedication right there."
When asked about Fillion's remark, Cena shot back, "What I want to know is, why is Nathan stalking me? He may be right, he may be wrong, but how has he kept track of my whereabouts for weeks?"
Co-star Margot Robbie, who portrays Harley Quinn in the film, also spoke with ET, and couldn't believe Cena had donned the outfit to the grand premiere.
"He stole that costume!" Robbie exclaimed. "I didn't even know we were allowed to do that! I did not know we could steal our costumes, and I didn't steal mine. I should have done that, I would have worn it tonight."
Directed by James Gunn, The Suicide Squad -- starring Cena, Robbie, Fillion, Idris Elba, Viola Davis, Michael Rooker, Joel Kinnaman, Jai Courtney, Pete Davidson, Daniela Melchior, David Dastmalchian, Storm Reid, Sylvester Stallone and Steve Ageee -- hits theaters Aug. 6 and is available for streaming on HBO Max.