The 27-year-old from Otley, resplendent in the world champion’s rainbow jersey, claimed a second win from two races in 2016 after her victory in last weekend’s Omloop Het Nieuwsblad in Belgium.
Armitstead (Boels-Dolmans) was part of a three-rider escape and accelerated up the final climb to the Piazza del Campo in Siena to secure the victory in the opening race in the UCI’s inaugural Women’s WorldTour.
Poland’s Katarzyna Niewiadoma (Rabo Liv) was three seconds behind in second place and Sweden’s Emma Johansson (Wiggle High5) was 10 seconds further back in third in the 121-kilometres race, much of which takes place over gravel roads.
“It’s amazing to win the first UCI women’s WorldTour event and this race is absolutely special,” said Armitstead.
“After winning in Belgium last week, thankfully I’m not affected by the curse of the rainbow jersey. I managed to honour it again today.
“We’ve shared the work in the last 10km with my two breakaway companions and I pulled away on the climb. It worked out really well.”