Hull hit the crossbar three times in a one-sided first half, before Craig Fagan eventually gave them the lead six minutes into the second half.
However, Leicester dominated the closing stages of the game and deservedly drew level through McCarthy 20 minutes into the second half.
Leicester started brightly and only an excellent tackle from Damien Delaney denied Mark De Vries, but then Hull took a grip of the game.
A superb cross from Stuart Elliott was headed on to the top of the crossbar by Fagan and then Elliott himself headed on to the other side of the bar, following a free kick from Andy Dawson.
Hull continued to threaten and visiting goalkeeper Robert Douglas produced an excellent save diving to his left to deny Fagan before Elliott's thumping header grazed the top of the woodwork yet again.
Leicester were a threat down the right-hand side and a pinpoint cross by Momo Sylla found De Vries who was denied by Boaz Myhill. Hull snatched the lead with their first attack of the second half. Jason Price only half-cleared Dawson's corner away and Fagan turned a left-footed volley home from six yards.
However, the visitors equalised when Richard Stearman swung in a cross from the right and the unmarked McCarthy scored from point-blank range. Leicester went close to snatching a winner in the closing stages when, firstly, Stearman's header was nodded of the line by Danny Coles.
Joe Hamill then burst through only to see his drilled right-foot shot from close range brilliantly parried by the Hull goalkeeper.