The Super Tuesday results in North Carolina will be closely watched for signs of each candidate's strength in one of the potential battleground states that could decide the November general election.
The win, mostly seen as symbolic, inoculates Haley from criticisms that she is unable to win a single primary race, though she still faces near-impossible odds to win the Republican nomination.
Trump won the primary convincingly on Tuesday, securing 12 of 16 delegates up for grabs. He took all of Michigan's remaining 39 delegates at stake on Saturday.
Trump's victory on Saturday was not a complete blowout but he still defeated Haley by a comfortable 20 percentage points on her home turf.
Haley had hoped that South Carolina's "open" primary would lead to turnout among independents, and some Democrats who are determined to stop Trump
Haley's husband, Michael, is currently serving in a voluntary deployment in Africa.
Haley, the last remaining rival to frontrunner Trump for the Republican presidential nomination, was the only major Republican candidate contesting the party's Nevada primary on Tuesday.
For Republican voters in Nevada, Tuesday's Republican ballot only has former UN ambassador Haley as a major candidate. She is therefore all but guaranteed to win, but it's largely meaningless.
Nikki Haley, a former South Carolina governor and UN ambassador under Trump, is running a distant second to Trump in opinion polls but has vowed to go on challenging him for the nomination.