CNN INSTANT POLL: Hillary Clinton won in a landslide
Sixty-two percent of 521 respondents said the Democratic nominee won the political showdown.
Twenty-seven percent of survey participants thought the winner was Trump, the Republican nominee.
CNN's political director David Chalian, however, cautioned that the poll "definitely skews Democratic" because of the sample, which was approximately 10% more Democratic than a normal CNN poll would use.
Chalian said the margin of error was about 4.5%.
The instant poll appeared to line up with what two focus groups also found. Both focus groups, one run by CNN and the other organized by GOP pollster Frank Luntz, concluded Clinton was the clear winner of the debate.
Heading into the debate, both Clinton and Trump were deadlocked nationally.
Monday's debate at Hofstra University was the first of three debates set to take place before voters cast their ballots in November.