Appleby said: "Other clubs were interested but basically this is the best opportunity I've ever had.
"I have under-achieved in my career so far but with the right equipment - and the right backing - I know I can do great things. I have a lot of confidence in my ability and I know I can please the Hull fans. I'm looking forward to the big match atmosphere week-in, week out.
"It's always been my ambition to play in front of 15-20,000 fans every week and that could happen at a club like Hull."
He also paid tribue to Jan Molby, who managed him at Swansea and Kidderminster previously.
Meanwhile, the Harriers' French defender Abdou Sall is being touted as a possible City target. However, while Molby would like to bring the 21-year-old to Boothferry Park, a move looks unlikely. City are not the only club showing interest, and it is thought that Kidderminster are looking for a fairly large transfer fee to let him go.
His agent Mark Cooper said: "The player wants to play at the highest level he can. It's a question of whether Kidderminster want to cash in on him now or risk losing him in a year's time for nothing when his contract expires. A lot of clubs have shown an interest. Derby and Rushden have watched him."
Molby said: "I don't know whether Kidderminster would want £100,000. I haven't spoken to them and I have no plans to either. At the end of the day, though, it's a lot of money for a Third Division defender.
"A lot of good centre halves will be on the market this summer and they will be available on free transfer."