On the final day of the slippery race in Cardiff, the Ford driver remained nearly half a minute ahead of Frenchman Sebastien Loeb of the Citroën team after winning the third stage of the morning.
Eight-time world champion Loeb began the day behind Petter Solberg in third place but moved ahead of the Norwegian after winning stage 15.
Loeb still on track for No. 9
Loeb still leads the current championship season. The Rally of Great Britain is the 10th event in this year's World Rally Championship.
Latvala’s Ford teammate ended up in third place, less than a second behind Loeb. Finland's Mikko Hirvonen was fifth behind Norwegian Mads Östberg.
Latvala's victory was his second in succession in Britain, but his first in seven months. It ended a five-race winning streak by Loeb going back to April. The Frenchman could clinch his ninth world title three weeks from now on home turf.