Phillips is a 23rd commitment in Clemson's 2019 class, moving the Tigers back into the top-5 in the 247Sports Composite.
Phillips had said he made up his mind in June - shortly after posting his Clemson offer on social media - but held off on announcing a commitment until his birthday. The other finalists were Oklahoma and Alabama.
"This recruiting thing is great until you have to choose one school," Phillips posted on Twitter. "It took countless prayers, and long conversations with people I love! I understand it can only be one. I always knew where my heart was, and it has never changed. The wait is over, I've decided to continue my academic and athletic career at Clemson University!"
Clemson moved up one spot to No. 5 in the 247Sports Composite rankings - above Oklahoma - with its 23rd commit in the 2019 class.
More from Lawrenceville and Phillips' announcement coming up on TigerNet.com.