The Scot, who has set herself the target of claiming the world title in Kona this year, was lying second at the start of the half-marathon run stage, almost three minutes behind the defending Annabel Luxford. However, she cut steadily into that lead before easing ahead with 6km left and eventually sealed victory by three minutes in a time of 4hr 12min 42sec.
"I can't say I ever plan these things; they just kind of happen," Morrison said. "I plan to race hard and see what happens. I did know that it would come down to a foot race, so that wasn't unexpected. I'm just very happy to have had such a strong start to the season."