The statement comes just one week after Fauci said it's "too soon to tell" if families should gather together for Christmas in December.
The government’s top infectious diseases expert told CNN’s "State of the Union" that parents can safely take their kids trick-or-treating outside this year if coronavirus cases and deaths continue their decline across the country.
"You can get out there – you're outdoors for the most part, at least, when my children were out there doing trick-or-treating – and enjoy it," Fauci said. "I mean, this is a time that children love. It’s a very important part of the year for children. I know my children enjoy it.
"Particularly if you're vaccinated," he added. "If you're not vaccinated, again, think about that you'll add an extra degree of protection to yourself and your children and your family and your community. So it's a good time to reflect on why it's important to get vaccinated.
"But go out there and enjoy Halloween as well as the other holidays that will be coming up," he said.
A COVID-19 vaccine has not yet been approved for children under 12, but Pfizer has asked for government approval of its vaccine for kids ages 5 to11.
Last year, Fauci, the director of the National Institute of Allergy and Infectious Diseases, advised parents not to allow their children to go door-to-door, or to at least make a face mask as part of their costume.
The Centers for Disease Control and Prevention last year labeled traditional trick-or-treating a "high risk" activity and advised parents to leave candy at their front door or driveway to minimize contact with strangers.