The Tory billionaire won 29,461 votes against Kramer’s 25,370 in the West London seat.
He said: "We held a very positive straight campaign. It comes down to positive, hard work."
Kramer said on her defeat: “You have chosen someone else and that’s the way it goes.”
Meanwhile Harriet Harman extended her majority in Camberwell, south London, by 4,000 votes.