NBA Star Jaylen Brown Signs With Kanye West's Donda Sports

The superstars are lining up to work with Kanye West -- TMZ Sports has learned Boston Celtics guard Jaylen Brown is the first pro athlete to ever sign with Donda Sports.

As we previously reported, future Hall of Famer Aaron Donald became one of the first big names to go public with his decision to partner with Ye for off-field ventures ... saying it was a "no-brainer" to join forces.

But as it turns out, Brown was way ahead of AD ... becoming the first athlete to ever sign with Donda, we're told.

Sources tell us Ye and Brown have been tight for a while now, but things were made official after West attended the Warriors vs. Celtics game in March.

The signs were there -- the two posed together postgame ... and in fact, Brown was spotted wearing a Donda Sports hoodie while hanging with A$AP Ferg afterwards.

So, why 25-year-old Brown?? We're told Donda eyed the Eastern Conference champ because of his intelligence, social activism and charitable work ... as well as his success on the court.

On top of that, the deal was especially important to Ye because Jaylen is a God-fearing man ... and his mother emphasized the importance of education at a young age, just like Donda.

We're told Ye thinks Brown is underappreciated ... and wants to bring him to "superhero" status during his career and long after his playing days.