The Houston Texans defensive end is tying the knot to his longtime girlfriend Asha ... and it's all going down at the NYC Public Library -- a historic landmark and one of the most beautiful buildings in the city.
We're told the guest list is around 200 and will include several of Devon's NFL friends -- including Pro Bowler Carlos Dunlap. In fact, Bengals defensive lineman Brandon Thompson is one of his groomsmen.
Of course, Leah is the flower girl!!
BTW, we're told the couple waited 2 years to get married ... until Leah was healthy enough to walk down the aisle. Amazing, right?!