"We've been keeping this a secret for awhile now," Murgatroyd said during a Tuesday morning appearance on Good Morning America with Lowe and his new fiancee.
"I am so tired of keeping secrets," Lowe joked. "But now they're all out!"
"And now I imagine you get a little training for the [wedding reception] first dance?" Lara Spencer asked Lowe.
"Exactly! That's why I signed up," Lowe replied.
"When we have our big day, hopefully I'll make her proud," Lowe said, gesturing to Giudici. "Won't make a fool of myself on the dance floor."
"You've had no time, zero time, to go from [The Bachelor] to [Dancing with the Stars]. That requires an awful lot of practice," Sam Champion told Lowe, turning to Murgatroyd. "Is he going to be ready?"
"Absolutely, he's going to be ready," Murgatroyd said with a big smile.
ABC revealed at the time the "mystery" contestant would be announced at a later date -- prompting speculation it would be Lowe, whom TMZ had previously reported would be part of the reality dancing competition's cast, because his The Bachelor season was still airing.
Lowe will be the second Bachelor and fourth The Bachelor franchise participant to compete on the reality dancing competition, following in the footsteps of former The Bachelor star Jake Pavelka, former The Bachelorette star Trista Rehn, and former The Bachelor bachelorette Melissa Rycroft.