"Over the last 5 days I have been working remotely and self-isolating, testing negative every day through yesterday. Today, I tested positive for COVID-19 and am in quarantine," Miller said in a statement.
He is the latest caught up in an outbreak at the White House that has seen a growing number of individuals, including Trump, infected with the virus.
Miller's wife, Vice President Mike Pence's communications director Katie Miller, tested positive for COVID-19 in May.
She tested negative on Tuesday morning but flew with Pence to Salt Lake City, Utah, for the 2020 vice presidential debate scheduled for Wednesday out of an abundance of caution, reports said.
Devin O'Malley, Pence's press secretary, tweeted on Tuesday evening that the vice president had tested negative again in the afternoon.
"Vice President Mike Pence is encouraged to go about his normal activities and does not need to quarantine," according to a memo written by his doctor.