Over the course of nine years, Julianna Pena’s UFC career has come full circle.

Back in 2013, she followed up months of filming “The Ultimate Fighter” with a victory to win the 18th season of the reality series.

And this Saturday, after starring on the 30th season of “TUF” as one of the opposing coaches, she will look to cap the experience off with a second consecutive victory over Amanda Nunes and, in the process, defend her bantamweight championship for the first time. The rematch of December’s all-time upset win by Pena (11-4, eight finishes) serves as the pay-per-view headliner for UFC 277 (10 p.m. Eastern) at American Airlines Center in Dallas.

“Being that I was on it that first season, I was very comfortable in the settings and the environment,” Pena told The Post over the phone earlier this week. “The atmosphere was filled with people that were watching me when I was a 23-year-old girl being on the show, so it was very familiar. It was a familiar territory to me, and I was very much in my comfort zone.”

Being a coach instead of a cast member certainly makes a difference, too. Fighters on the long-running program stay together in a house, isolated from family and friends. When Pena won nine years ago, she lived alongside women such as Raquel Pennington and Roxanne Modafferi, who went on to fight for UFC gold, as well as women’s MMA pioneer and current WWE star Shayna Baszler.

“TUF” is a lot more comfortable as a coach. This time, Pena was had the freedom to come and go as her responsibilities at the gym began and ended for the day — understandably, the biggest difference for the current 135-pound champ. Way better setup than that of the fighters she coached, stuck in a situation she compared to a prison of sorts.

“I got to be with my family. I got to go to my daughter and my mom and have a regular life outside of the jail-type sentence that the fighters were in,” said Pena, a mother to a 4-year-old born about one year after her first UFC loss to future flyweight champ Valentina Shevchenko. “That was the biggest takeaway for me was that I didn’t have to be confined into one house with [16] kids. It was just me and my family, and I got to live the normal day-to-day life that they didn’t get to do.”

Know what else Pena gets to do that those up-and-comers don’t yet? Walk around with a shiny gold UFC title belt, the one she claimed after stunning the MMA world with a submission of Nunes (21-5, 17 finishes) at the end of 2021. One of the greatest betting underdogs to ever win a UFC title fight, Pena may have got the finish with her bread and butter grappling. but she turned plenty of heads — figuratively for most, literally in Nunes’ case — by fearlessly standing and trading with the hard hitting defending champion. Pena steadily gained the upper hand in a wild brawl before a tiring Nunes succumbed to a rear-naked choke in the second round. 

Pena has watched the fight in its entirety a “handful” of times, and she’s been exposed to highlights of the ending sequence plenty of times. It wasn’t always pretty, but she says she was prepared for that as a necessary evil to get the fight where she wanted it to be, and it is once again her intention to engage with Nunes — who still holds the featherweight title — in the pocket and go from there.

“Before the [first] fight, I knew that it was going to take standing in the pocket and going toe to toe with her in order to get it to the ground, and it can’t be in reverse,” said the 32-year-old from Spokane, Wash. “All fights start on the feet, and the most important thing for me was to know you’re going to get hit; you are going to take some shots; you’re going to give some shots. But you cannot stray away; you cannot take a step backwards, and you cannot retreat. You have to go forward. You have to meet fire with fire, and you have to stand.”