McKinsey's 400 senior partners elected Mr Barton to serve a three-year term when Ian Davis retires in June. He will be able to stand for re-election for a second and final three-year term in 2012.
He defeated the long-time contender for the job, Michael Patsalos-Fox, in the final run-off and will be the 11th partner to lead the business since it was founded in 1926. Aged 46, he is a year younger than Marvin Bower, McKinsey's most famous managing director, when he took up the role in 1950. Bower remained in the job 17 years.
Amid tough market conditions for consultancies, Mr Barton will be under pressure to make sure McKinsey continues to justify its reputation and fee structure.