Biden leads Trump 46 percent to 38 percent, a 2-point gain for Biden compared to a previous survey conducted earlier this month.
The survey released Friday found that 8 percent of respondents were undecided in the race, a slight uptick from the previous poll, while 4 percent said they prefer a different candidate and 3 percent don't plan to vote in November.
Biden holds a 10-point lead over Trump among independent voters in the poll, 39 percent to 29 percent. That's an increase from a 2-point lead he held in the survey earlier this month.
Slightly more Democrats in the poll said they'd back Biden in November than Republicans who said they would support Trump, though both candidates had comparable levels of support from within their parties.
Among Democrats, 85 percent said they would back Biden if the election were held today, while 81 percent of Republicans said they would vote for Trump.
The survey was conducted Aug. 15-18, with some responses gathered on the first two days of the Democratic National Convention this week, where Biden formally accepted his party's nomination.
The survey of 2,840 registered voters was conducted online and has a margin of error of plus or minus 1.84 percentage points. The previous Hill-HarrisX poll was conducted Aug. 11-14.