AP Photo/Kathy Willens
The former secretary of state and senator from New York was leading Bernie Sanders, a Vermont senator, by a significant 60.5% to 39.5% margin when the race was called just after 9:30 p.m. ET.
Heading into the primary, Clinton was leading Sanders by nearly 12 points in the RealClearPolitics average of several polls.
It's a significant win for Clinton, as Sanders campaigned hard in the state in an attempt to close the gap with the former secretary of state.
With nearly 250 delegates on the line in the Democratic race, both Clinton and Sanders sharpened their critiques of one another in the two weeks between the Wisconsin primary earlier this month and Tuesday's vote.
Clinton said Sanders "hadn't done his homework" after a highly criticized interview the candidate conducted with the Daily News, a New York tabloid. Sanders would later fire back saying that Clinton might be "unqualified" for the presidency, citing her taking in large sums of Wall Street cash, among other points. He later softened his stance, but questioned Clinton's "judgment."
The back and forth hit a boiling point in Thursday's Democratic debate, held in Brooklyn, where the two candidates exchanged their fiercest blows yet.