While waiting for an Uber outside her home in Rio de Janeiro, Viana was approached by a man who, armed with a fake gun, attempted to steal her phone.
Uncowed by the would be thief, Viana aimed two punches and a kick at the man before subduing him with a chokehold from behind.
The Brazilian fighter continued to restrain him until the culprit was treated for his injuries and taken to the police station, where Viana filed a report.
"I remember every single thing. It is like it all happened yesterday," Viana told CNN Sport via email. "The attention didn't last for long, but people still ask me about it."
Her story was covered by media outlets across the world and was shared thousands of times on social media.
Pictures from the alleged incident, reportedly taken by Viana, even appeared on UFC president Dana White's Instagram account showing the man's gruesome injuries.
Dealing with her new found fame was something Viana enjoyed and she tried to use it as an opportunity to empower other women who may find themselves in a similar situation.
But she was also criticized with some arguing that the incident was not an example of what to do in such a scenario.
"I felt it was cool to show women that we are able to defend ourselves, but I also faced a lot of criticism," reflected Viana.
"I ignored most of it, it was my life that was in danger and I feel like I did the right thing.
"Doing the right or the wrong thing, there will always be criticism. Overall, all the attention was really good for me."
At the time, the Rio police department were unable to confirm the individuals involved in the incident but told CNN Sport that an attempted robbery had taken place.
Knowing the media flurry was likely to be short lived, Viana tried to keep herself grounded and concentrate on her career.
However, in the year after her ordeal, the fighter lost both of her two bouts.
Now, as she prepares for her next fight against American fighter Emily Whitmire on March 3, she is determined to get her title aspirations back on track.
"I'm really confident. I want to be the UFC champion. That is my focus and I can't wait to make it happen. I'm working really hard," the 27-year-old said.
"I'm training everything and will be ready for anything. I completely believe that I can win. I'll try to impose my game plan and try to finish this fight as quickly as possible."