The 19-year-old, who has made just one appearance for Liverpool, in a Europa League clash against Rabotnicki in July, could come up against Anfield team-mate Paul Konchesky, currently on loan at Nottingham Forest, in his debut on Saturday.
Amoo told Hull's official website: "I found out about Hull's interest on Friday. I drove down and watched the game (against Cardiff) on Saturday and signed after that.
"Once I heard about it (Hull's interest) I was up for it. I'll be playing in a good side doing well. It's a good chance to progress."
Amoo, who has just completed a month on loan at MK Dons, where he made three substitute appearances, is relishing a possible heads-up with Konchesky at the weekend.
Amoo added: "I'm looking forward to it, Forest away. Konchesky's playing left-back, so it could be a good game."