Brady has enjoyed a high-profile career since appearing in a docusoap about Birmingham City struggling to enter the Premier League and writing a football column in The Sun.
She is joined on the board by Andy Mollett, chief financial officer of EMI Music Publishing.
Channel 4 chairman, Luke Johnson, said: "I'm delighted the recruitment process has turned up two such distinct and dynamic new TV directors. Andy has an impressive and highly relevant track record in the media sector, while Karren is rightfully admired for turning Birmingham City into a plc and building it into a Premiership powerhouse."
The appointments replace outgoing non-executives, Endemol UK chairman, Peter Bazelgette, and Trinity Mirror chief executive, Joe Sinyor, after three and six years on the board respectively.
Brady and Mollett take up their directorships with immediate effect.
The duo join at an important time for Channel 4, amid discussions of a possible merger with Five and debate over the option of privatisation.
For the first time since its 1982 launch, Channel 4 does not have a member of the independent production sector on its board. This could potentially bring the broadcaster some criticism because its schedule consists of 100% independent production programming.
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