Hudson joined Charlton on a three-year deal from Crystal Palace last summer and made 45 appearances after being named captain.

However, following the Addicks' relegation to League One, the 27-year-old has been able to secure a move back to the Championship.

Charlton will receive an initial £1.075million fee, plus a further £250,000 if Cardiff win promotion to the Premier League, while there is also a sell-on clause in the deal.

He will help to fill the void created by Roger Johnson's sale to Birmingham City and is looking forward to linking up with the Bluebirds.

"I'm excited and pleased to have completed the move," Hudson told the club's official website.

"I met the manager and the chairman and they showed me around the new stadium and the training ground and it looked superb.

"I'm looking forward to linking up with the lads now and getting started. Cardiff went pretty close last year and hopefully this time around we can take that one step extra.

"Cardiff is a great club and whenever I have played here the supporters have always been superb for the home team and I'm looking forward to running out at the new stadium with a full house - the atmosphere I'm sure will be fantastic."