ABC announced the news via press release on Thursday, revealing that Chris Harrison will host a three-hour special on Monday, Jan. 7 to celebrate Underwood's premiere.
"We've done live before," Harrison told ET's Lauren Zima of the special during The Bachelor's junket in Los Angeles on Thursday. "For Chris Soules' season, we kind of did this red carpet type thing. We've kind of learned all our mistakes, and this is the culmination of all that."
"We wanted to have this awesome, massive viewing party. The Bachelor draws viewing parties unlike any show on TV. It's kind of like the Super Bowl, everyone watches together, so [we asked], 'What can we do to pay homage to our fans, but also include them?'" he continued. "I will say that it's going to be a party unlike any other."
The host said that he'll be hosting the show live from a "historic" place in Los Angeles and that it won't have the look and feel of a stage, like fans have seen on Women Tell All or After the Final Rose. "It's going to be a party, and that party's going to go from the East Coast all the way to the West Coast, and all the places in between," he promised.
Harrison teased that he'll be bringing some good wine, and encouraged fans to stay tuned for more details on how to participate. "We are very much going to involve Bachelor Nation," he said.
The Bachelor is definitely going big for Underwood's season, which will include celebrity guests like Megan Mullally and Nick Offerman, Billy Eichner and Terry and Rebecca Crews. Fred Willard will make another cameo appearance to commentate on a date with Harrison, while singers Tenille Arts and Brett Young will deliver musical performances.
Celebrity appearances aside, Harrison promised that fans will be pleased with Underwood's season. "I just think there were so many more layers and a dynamic set to this season. It was just fun to dive into," he said. "There was a lot of times when he pushed back, and it made us think and made us adjust course. The season took a lot of twists and turns, that it's very raw and just open. I don't think it will feel very produced to you."
The Bachelor returns Monday, Jan. 7 at 8 p.m. ET/PT on ABC -- join ET's Bachelor Nation Facebook group here.