Zach Bryan has officially broken the attendance record at Robert Kraft's Gillette Stadium ... on the very night he wore a "Free Palestine" shirt for the second time!

Waiting for your permission to load the Instagram Media.

The stadium actually broke the news themselves ... sharing on Instagram that 73,538 fans had attended his show.

Many fans, including Bella and Gigi Hadid's sister Alana, were quick to point out that the photos the stadium posted avoided close-up shots of Zach's shirt.

We reported earlier ... the "Pink Skies" singer and his entire band wore pro-Palestine shirts and jerseys for both nights at the Foxborough, MA venue.

The apparel is actually from Wear the Peace -- a humanitarian organization that's all about helping people in Gaza.

Waiting for your permission to load the Instagram Media.

Since Kraft played a major part in ousting Macklemore from Ed Sheeran's tour over pro-Palestine comments ... his stadium has been the one making headlines.

Both of Ed's concerts at the arena were called off due to a nor'easter ... and now, Zach shattered a record while wearing a "Free Palestine" shirt. You just can't make this up!