Kumar, who is also chief executive of the charity's subsidiary development company, Cancer Research Technology, is the first non-medical professional to lead Britain's biggest charity.
A CRUK spokesman said: "Harpal was behind the recently opened Cambridge Research Institute and our network of experimental cancer medical centres.
He has also helped to position the charity as a world leader in drug development and trebled the income of Cancer Research Technology."
Kumar said: "I'm delighted and honoured to be appointed chief executive of CRUK. I'm passionate about our vision to beat cancer and the ambitious goals we are setting ourselves."
According to a Third Sector survey (Third Sector, 22 March 2006), the only other non-white leader among the top 50 charities is Daleep Mukarji, director of Christian Aid.
Krishna Sarda, chief executive of the Ethnic Minority Foundation, which campaigns for better representation of ethnic minorities in the voluntary sector, said: "CRUK should be congratulated, but we still have to remember that the sector is predominantly white, male and middle class. Diversity suffers from a great deal of indifference within the sector."