Cardiff will allow long-serving Kevin McNaughton to leave this summer along with Danny Gabbidon and Nicky Maynard.
Highly-rated Atletico Madrid midfielder Saul Niguez has signed a new five-year contract.
Hull have confirmed the signing of Shane Long from West Brom, taking their week's spending to around £14million following the capture of Nikica Jelavic.
Jelavic was signed from Everton for an initial £6.5million, rising by an additional £1million should the Tigers stay in the Barclays Premier League, and the undisclosed deal for Republic of Ireland striker Long is understood to be worth a similar amount.
West Brom agreed a fee for Long on Thursday, with the player having a medical with Hull on the same day.
Personal terms were finalised on a three-and-a-half-year deal on Friday morning and Long's paperwork was cleared in time for the 26-year-old to be available for the Barclays Premier League trip to Norwich.
Long was close to signing for the Tigers on deadline day in September and was at the club's training ground when West Brom pulled the plug as their own pursuit of Romelu Lukaku faltered.
Manager Steve Bruce maintained an interest in the player and received the green light from new Baggies boss Pepe Mel when a new enquiry was made this month.
Long, who joins fellow Republic of Ireland internationals David Meyler, Robbie Brady, Paul McShane and Stephen Quinn in East Yorkshire, said: "I finally got the deal signed. I've met all of the lads today, and everybody seems really friendly.
"It's a club that's on the up, and I'm delighted to be a part of that.
"I'm lucky that I've had a few inside informers letting me know what it's like up here. They all love it up here, and they're excited by what is happening at the club.
"After meeting the manager, and respecting what he's done as a player and a manager, I was happy to start a new part of my career here and hopefully I can score a few goals to take us further up the league."
Long's arrival completes a swift overhaul of Hull's forward line, which has laboured for goals so far this term.
Ivorian Yannick Sagbo has impressed with his hold-up play but found the net just twice, while on-loan Sunderland striker Danny Graham has struck a solitary goal in a disappointing spell.
Graham may yet be sent back to the Black Cats, while Matty Fryatt and Nick Proschwitz are available for transfer and have already attracted interest from in the Championship.
Long's scoring record is not spectacular but he has a track record in the division, with 19 goals in 60 Premier League starts for Albion.
He has three to his name this season, a fine effort against Chelsea and two against Aston Villa.
Graham is currently in possession of the number nine shirt worn by Long at The Hawthorns, with the new signing taking number 21.