Nikki Bella ain't letting an ankle injury get in the way of her and twin sister Brie's big WWE comeback at WrestleMania 42 this weekend -- she even walked the red carpet in a boot!

The WWE Hall of Famers were all smiles, chatting it up with each other on the red carpet Friday night ... looking strong and sexy in their respective ensembles. But, there was no hiding the giant boot Nikki has on her left foot, resulting from an injury sustained during the March 27 SmackDown.

Rumors are swirling online Nikki won't be cleared to compete in the WE Women's Tag Team Championship fatal four-way match alongside Brie Saturday night ... but she's given no indication that she'll drop out.

She and Brie even celebrated their attendance during their special edition of "The Nikki & Brie Show," during which Nikki enthusiastically said ... "WrestleMania, we are back in action. 11 years later, Brie. Over a decade, to remind everyone."

It seems like she has every intention of being back in the ring ... and we can't blame her!

Nikki hasn't competed at a WrestleMania since WrestleMania 33 ... and Brie's in-ring appearances since 2016 have been quite limited.

We've reached out to Nikki's reps for comment ... so far, no word back.