The country singer is married to The Voice coach Blake Shelton and will serve as a mentor for his team during the second season, which is currently airing Monday nights on NBC.
Speaking to social media corespondent Christina Milian, she said: "I've been watching from behind the scenes for all of last season so it's cool to be part of it."
Lambert continued: "I was a really bad, I guess, backseat driver last year. Blake would be doing things and making decisions and I'd always be popping up. He was like, 'You'd probably be really good at it, you should come on as a mentor if you have the opportunity'."
She added that her own experience as a contestant on Nashville Star when she was 19 years old helped her understand what The Voice contestants are going through.
"That was a singing competition so I know how much pressure it is," she said. "It made me realise I learned a lot over the last few years about performing and being out there."
Watch Miranda Lambert talking to Christina Milian below:
Lambert said that she is looking forward to watching the upcoming battle rounds but admitted that she couldn't imagine having to take part if she was a contestant.
"It seems really intense and really hard," she said. "I guess a lot of them have become friends and having to go up against your friends with one of you going home is scary."
The other guest mentors this season are: Kelly Clarkson, Babyface, Ne-Yo, Alanis Morissette, Lionel Richie, Robin Thicke and Jewel.
The Voice airs Mondays at 8/7c on NBC
Browse pictures from the last blind auditions below: