The 18-year-old has established himself in the Wycombe team this season, making 17 appearances in League One.
Harris, who has signed a three-and-a-half year contract, won League Two's apprentice of the year award for the 2010-11 season.
"It's a good deal for all parties," Wycombe manager Gary Waddock told the club's website.
Cardiff manager Malky Mackay has made signing a winger a priority in the January transfer window.
He has failed in his attempts to prize Craig Noone from Brighton, while a bid for Blackpool's wide man Matt Phillips has also been rejected.
Harris broke the record as Wycombe's youngest player when he made his debut in 2009, aged 16 years and 201 days. That record has subsequently been taken from him by Jordan Ibe in 2011, who was 15 years and 244 days when he featured in a Carling Cup tie.
Striker Ibe, now 16, joined Liverpool earlier in the January transfer window.
Waddock added: "Like Jordon Ibe recently, we didn't want to stand in the way of Kadeem and the opportunity for him to play at a higher level.
"I've thoroughly enjoyed working with Kadeem during my time at the club and I wish him every success for the future."

The Â£45m facility, to be built at Sutherland Drive in Kilmarnock, will house primary and secondary schools, a Gaelic school and a childcare centre.
East Ayrshire Council said it would ask permission from the McIlvanney family to name the campus in his honour.
The renowned writer was born and educated in Kilmarnock.
Council leader Douglas Reid said he was delighted to be able to "preserve" the William McIlvanney name in Kilmarnock as the writer was "passionate about the provision of good education for young people".
McIlvanney became an English teacher after graduating from Glasgow University but changed career in 1975 to write full time.
He gained immediate recognition with the publication of his first novel - Remedy Is None - and through other works he earned the title of "Godfather of Tartan Noir".
McIlvanney wrote the acclaimed Laidlaw trilogy and other Glasgow-based works such as Docherty and The Big Man.
He was also an influential poet, journalist and broadcaster, and contributed to political and sporting life in Scotland through a series of columns and TV programmes.
The novelist died at his Glasgow home on 5 December.

Sherwood took over in February with Villa in the bottom three and led the club to Premier League safety and 17th.
"We gave the fans nothing to cheer about today but I promise them it will get better," Sherwood told BBC Sport.
"We've stayed in the division but we have a losing mentality. We don't want to be scraping relegation next season."
Villa were outclassed by Arsenal, whose victory at Wembley saw them become the most successful club in FA Cup history with a 12th title.
Sherwood acknowledged his side "came up short" against the Gunners, adding that his players "need to learn how to be winners".
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"Of course we believed we could win this but I can't make any excuses," the 46-year-old added. "It's a learning curve and we need to build a new team.
"Some of the boys have already been told they won't be here next year or they can find other clubs. I want to be honest with players and don't want to be stringing experienced players along.
"But it's not just new additions to the squad but also getting some of the players we do have to play in a different way, to change the mentality of a few of them."
Villa captain Fabian Delph agreed Arsenal had been worthy winners and also stressed the importance of Villa finding a "winning mentality" next season.
"We were up against it, we tried to dig deep but their quality shone through and we struggled," the 25-year-old said.
"The manager said that we had it in us to cause an upset but we couldn't find the performance. But a few weeks ago we would have snapped your hand off to stay in the league and get to this final. Now it's important that we get a winning mentality.
"We have to forget about today, some players will come through the door to strengthen us and I am sure we will get better and better."
Cardiff City have signed Wycombe Wanderers winger Kadeem Harris for an undisclosed fee.
[NEXT_CONCEPT]
A schools campus in East Ayrshire is set to be named after the celebrated Scottish novelist William McIlvanney, who died last month aged 79.
[NEXT_CONCEPT]
Aston Villa manager Tim Sherwood promised to rid the club of its "losing mentality" after suffering a 4-0 defeat by Arsenal in the FA Cup final.