No wonder Knicks star Jalen Brunson has such high basketball IQ — he has a giant head!

His teammate Josh Hart — who was Brunson’s roommate in college at Villanova University — dished on the size of Brunson’s cranium while appearing on an online gameshow this week.

Hart — who recently launched the “Roommates Show” podcast with Brunson — was asked on Bilt Rewards’ “Rent Free” to “give us an embarrassing story about Jalen.”

After Hart, 28, mused, “That I can say in the public?” — he dished to “Rent Free” host and Bilt Rewards CEO Ankur Jain about Brunson’s astonishing hat size.

“The other day… I bought these hats,” Hart recalled.

“They were one size fits all,” he added. “But they didn’t fit [Jalen’s] head — because his head is too big.”

He also said, “That’s kind of a little embarrassing, because he has a huge head and really little ears.”

Brunson, 27, has led the Knicks on a run that has put him in the conversation as a possible NBA MVP. 

The Bilt Rewards show invites celeb guests answer questions to win rent for the app’s members — and has featured Lance Bass and Staten Island foodie influencer Danny Mondello.

The New York-based startup has a loyalty platform where users earn points on rent payments, and the company more than doubled its valuation to $3.1 billion recently.

NFL Commissioner Roger Goodell and former American Express CEO Ken Chenault have joined its its board.

Led by former Tinder exec Jain, the company racked up $200 million in its most recent funding round led by General Catalyst, The Post reported.