The two are paired with another married couple, Maks Chmerkovskiy and Peta Murgatroyd.
ET caught up with the dynamic duos on Wednesday, where Nick revealed what made him want to join the show, after previously telling ET he would "never" do it.
"Never say never, kids. Never say never," he shared. "This is a cool opportunity, obviously, but [even more so] to do it alongside this lovely lady and my wife on the show."
"I said I would never do this show, but then you find yourself thinking, 'How can I tell my 5-year-old, 'Don't be scared to go out for baseball, don't be scared to try tennis lessons,' when I myself am not practicing what I'm preaching?" Nick said. "I've never been a big dancer. I've always been a little bit scared of it, but that's probably all the more reason to be a part of this show."
"Hopefully the kids will enjoy it [and] they won't play favorites to Mama, and Daddy will get some love too," he added.
It seems Vanessa has already become a hot commodity, as Nick confessed to "getting advice" from his wife and bartering dance lessons for parenting lessons, while his partner, Peta (who called their partnership "TV gold"), is bonding with the former TV host over their new babies.
"Our babies are two to three weeks apart," Vanessa explained. "Shai [Chmerkovskiy] and Phoenix [Lachey] are born literally just weeks apart, and it's a beautiful journey to be able to go through it with someone that gets you, because it's deeper than just dancing."
"Nick's 43. I'm 36, and we've got three kids that want to play around and wrestle all day," she continued. "This is actually kind of training me to be a better mommy, so thanks, Maks."
"This is where I come in," Maks said. "I love this partnership. I think it's going to be great, just because I know what she needs... with all the stuff that's going on in their household."
The Lacheys and Chmerkovskiys couldn't be happier with their partnerships, but it's fans' nicknames for their dance battle -- ChmerLachey vs. ChmerLachey -- that could use a little work.
"Lachey-skiys [is] probably a little better," Maks offered.
"I like that," Vanessa added, revealing that the foursome plans to play nice until the finals. "We just want to get to the finals, and then apparently that's when they say the gloves come off."
Dancing With the Stars returns Monday, Sept. 18 at 8 p.m. ET/PT on ABC. See more on the upcoming season in the video below.