Campbell is now set to hold talks with the Premier League new boys after the Foxes met his release clause at the Cardiff City Stadium.
A number of clubs have been credited with an interest in former Manchester United youngster Campbell in the wake of Cardiff's relegation from the Premier League.
Cardiff were keen to keep Campbell, but are powerless to stop him moving on after Leicester became the first club to trigger his release clause.
Leicester have been busy already in the transfer market this summer, bringing in Matthew Upson and Marc Albrighton, and Nigel Pearson is hoping to add Campbell to his ranks.
Campbell was Cardiff's top scorer in all competitions last season and he is thought to be keen on a stay in the Premier League.