The Foxes slipped to a 2-1 Premier League defeat on the south coast on Sunday but will welcome Graham Potter's side to the King Power Stadium in the cup next month.
"This is a fantastic competition," Iheanacho told LCTV.
"Hopefully we'll get a chance to win games and get through and get to the end, but it will be a tough one also. Fingers crossed, we're looking forward to the games.
"Hopefully we won't get a cold night against Brighton again! It'll be a good game. We're looking forward to it.
"They're really good this season. Hopefully we'll give them a game at the King Power Stadium and we'll get through."
Goals from Ademola Lookman and Iheanacho sent Leicester through after a 2-0 win at Championship side Millwall.
"It was a sweet goal, a rocket, and we're happy with that," Iheanacho added about his stunning late strike.
"It was team work and we're happy going into the next round. We put the work in. We defended really well and we got the first goal early in the second half.
"It was a really tough game. They're a good side, they gave us a good game. It wasn't easy in the first half, but in the second half the space was there. We got our chances and we saw it through."
One bright spot for the injury-hit Lions was the performance of winger Connor Mahoney.
"I thought he played really well. It was as well as he's played for us," said manager Gary Rowett.
"We know Connor is a really talented player and what I've asked him to do is match that talent with work-rate and drive."